Composite material, ink, film and photoelectric device

Abstract

The invention discloses a composite material, ink, a film and a photoelectric device, and relates to the technical field of display. The composite material comprises a first core-shell quantum dot and a second core-shell quantum dot, the first core-shell quantum dot comprises a Type I type quantum dot, and the second core-shell quantum dot comprises one or more of a Type II type quantum dot and an anti-Type I type quantum dot. According to the composite material provided by the invention, the coupling strength of carriers and quantum dots can be enhanced, the transport speed of the carriers is increased, and injection and balance of the carriers are promoted.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and in particular, to a composite material, an ink, a thin film, and an optoelectronic device. Background Art

[0002] Currently, the widely used optoelectronic devices are organic light-emitting diodes (OLEDs) and quantum dot light-emitting diodes (QLEDs). Due to their excellent display performance such as self-luminescence, simple structure, ultra-thinness, fast response speed, wide viewing angle, low power consumption, and flexible display, OLEDs have become the mainstream technology in the field of display technologies. QLEDs have the advantages of saturated emission light color and adjustable wavelength, and high photoluminescence and electroluminescence quantum yields, and have become a strong competitor to OLEDs in recent years.

[0003] The structures of traditional OLED and QLED devices generally include an anode, a hole injection layer, a hole transport layer, a photoactive layer, an electron transport layer, an electron injection layer, and a cathode. Under the action of an electric field, the holes generated by the anode and the electrons generated by the cathode of the light-emitting diode move, are respectively injected into the hole transport layer and the electron transport layer, and finally migrate to the photoactive layer. When the two meet in the photoactive layer, energy excitons are generated, thereby exciting the luminescent molecules to finally generate visible light.

[0004] Currently, the optoelectronic conversion efficiency of optoelectronic devices is relatively low and needs to be further improved. Summary of the Invention

[0005] In view of this, the present application provides a composite material, an ink, a thin film, and an optoelectronic device.

[0006] The embodiment of the present application is implemented as follows. A composite material includes a first core-shell quantum dot and a second core-shell quantum dot. The first core-shell quantum dot includes a Type I quantum dot, and the second core-shell quantum dot includes one or more of a Type II quantum dot and an anti-Type I quantum dot.

[0007] Correspondingly, the embodiment of the present application further provides an ink, which includes a first core-shell quantum dot, a second core-shell quantum dot, and a solvent. Among them, the first core-shell quantum dot includes a Type I quantum dot, and the second core-shell quantum dot includes one or more of a Type II quantum dot and an anti-Type I quantum dot.

[0008] Correspondingly, the embodiment of the present application further provides a thin film. The material of the thin film includes a first core-shell quantum dot and a second core-shell quantum dot. Among them, the first core-shell quantum dot includes a Type I quantum dot, and the second core-shell quantum dot includes one or more of a Type II quantum dot and an anti-Type I quantum dot.

[0009] Accordingly, an embodiment of the present application further provides an optoelectronic device, which includes a first electrode, a photoactive layer, and a second electrode that are sequentially stacked, and the material of the photoactive layer includes the above composite material.

[0010] The composite material provided by the present application can enhance the coupling strength between carriers and quantum dots, increase the transport speed of carriers, and promote the injection and balance of carriers. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0012] Figure 1 It is a schematic diagram of a Type I quantum dot provided by an embodiment of the present application;

[0013] Figure 2 It is a schematic diagram of a Type II quantum dot provided by an embodiment of the present application;

[0014] Figure 3 It is a schematic diagram of another Type II quantum dot provided by an embodiment of the present application;

[0015] Figure 4 It is a schematic diagram of a Type I quantum dot provided by an embodiment of the present application;

[0016] Figure 5 It is an energy level schematic diagram of a Type I quantum dot;

[0017] Figure 6 It is an energy level schematic diagram of a thin film containing Type I quantum dots and Type II quantum dots provided by an embodiment of the present application;

[0018] Figure 7 It is an energy level schematic diagram of another thin film containing Type I quantum dots and Type II quantum dots provided by an embodiment of the present application;

[0019] Figure 8 It is an energy level schematic diagram of a thin film containing Type I quantum dots and inverse Type I quantum dots provided by an embodiment of the present application;

[0020] Figure 9 It is an energy level schematic diagram of a thin film containing Type I quantum dots, Type II quantum dots, and inverse Type I quantum dots provided by an embodiment of the present application;

[0021] Figure 10 is another energy level schematic diagram when the thin film provided by the embodiment of the present application contains Type I quantum dots, Type II quantum dots, and inverse Type I quantum dots;

[0022] Figure 11 is a flowchart of the preparation method of the ink provided by the embodiment of the present application;

[0023] Figure 12 is a schematic structural diagram of the thin film provided by the embodiment of the present application;

[0024] Figure 13 is a schematic structural diagram of the optoelectronic device provided by the embodiment of the present application;

[0025] Figure 14 is a schematic structural diagram of another optoelectronic device provided by the embodiment of the present application;

[0026] Figure 15 is an exciton fluorescence lifetime curve graph of the quantum dot solution provided by Example 1 and Comparative Example 1 of the present application.

[0027] Reference numerals:

[0028] Thin film 11; Quantum dot core layer 111, Quantum dot shell layer 112;

[0029] Photoactive layer 10; First electrode 20; Second electrode 30; First carrier functional layer 40; Second carrier functional layer 50. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a 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 creative efforts belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation manners described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0031] In the present application, unless otherwise stated, the orientation words such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are only used as labels and do not impose numerical requirements or establish an order.

[0032] In this application, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Here, A and B can be singular or plural.

[0033] In this application, "at least one" means one or more, and "a plurality" means two or more. "One or several", "at least one (item) below" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one (item) among a, b, or c", or "at least one (item) among a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0034] The various embodiments of this application can exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed 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 values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub - ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0035] The photoactive layer of traditional quantum dot optoelectronic devices uses single - component Type I quantum dots. For the core - shell structure design of Type I quantum dots, due to the strong confinement of the shell layer on the excitons in the core, and at the same time, the shell layer effectively isolates the core layer from the external environment, ensuring its high fluorescence quantum yield and stability. However, the Type I quantum dot heterostructure has non - equilibrium carrier transport characteristics, with a confinement effect on both electrons and holes, which affects the movement of both electrons and holes, resulting in an obvious transport difference of the carriers injected into the quantum dot thin film. At the same time, limited by the selection of carrier functional layer materials, it is difficult to regulate the carrier balance of optoelectronic devices prepared with single - component quantum dots as the photoactive layer, affecting the optoelectronic conversion efficiency and service life of optoelectronic devices.

[0036] The technical solution of this application is as follows:

[0037] In a first aspect, the present application provides a composite material, comprising a first core-shell quantum dot and a second core-shell quantum dot. The first core-shell quantum dot comprises a Type I quantum dot, and the second core-shell quantum dot comprises one or several of a Type II quantum dot and an inverse Type I quantum dot.

[0038] It can be understood that a core-shell quantum dot is a heterostructure nanocrystal composed of two or more semiconductor materials. According to the relative positions and arrangements of the energy bands of the core-shell semiconductor materials, the core-shell quantum dots can be classified into Type I quantum dots, Type II quantum dots, and inverse Type I quantum dots.

[0039] Please refer to Figure 1 , a Type I quantum dot refers to a quantum dot in which the conduction band energy level of the quantum dot shell layer 112 material is higher than that of the quantum dot core layer 111 material, and the valence band energy level of the quantum dot shell layer 112 material is lower than that of the quantum dot core layer 111 material. Since the bandgap of the shell layer is wider than that of the core layer, most photo-generated carriers are confined in the core. Due to the shell layer barrier, the probability of excitons being captured by surface defects is reduced, and the luminescence efficiency and fluorescence stability of the quantum dots are significantly improved.

[0040] Please refer to Figure 2 and Figure 3 , a Type II quantum dot refers to a quantum dot in which the conduction band energy level and valence band energy level of the quantum dot core layer 111 material are both higher or both lower than the conduction band energy level and valence band energy level of the quantum dot shell layer 112 material. Correspondingly, there are two cases for Type II quantum dots. When the conduction band energy level and valence band energy level of the quantum dot core layer 111 material are both higher than the conduction band energy level and valence band energy level of the quantum dot shell layer 112 material, the Type II quantum dot confines electrons and does not confine holes; when the conduction band energy level and valence band energy level of the quantum dot core layer 111 material are both lower than the conduction band energy level and valence band energy level of the quantum dot shell layer 112 material, it confines holes and does not confine electrons. Compared with Type I quantum dots, Type II quantum dots have a longer exciton decay period, which is beneficial to the spatial separation and transfer of carriers.

[0041] Please refer to Figure 4 , contrary to Type I quantum dots, an inverse Type I quantum dot refers to a quantum dot in which the conduction band energy level of the quantum dot shell layer 112 material is lower than that of the quantum dot core layer 111 material, and the valence band energy level of the quantum dot shell layer 112 material is higher than that of the quantum dot core layer 111 material. The bandgap of the core layer is wider than that of the shell layer.

[0042] The composite material provided by the present application includes Type I quantum dots, and one or more of Type II quantum dots and inverse Type I quantum dots. By incorporating inverse Type I quantum dots and / or Type II quantum dots into Type I quantum dots, the inverse Type I quantum dots do not confine electrons and holes, enabling the carriers to delocalize within the entire quantum dot range. After the carriers delocalize, their wave functions extend to the electron and hole wave functions of adjacent quantum dots, resulting in overlapping coupling, which can enhance the coupling strength between the carriers and the surrounding quantum dots and increase the transport speed of the carriers. The Type II quantum dots have hole or electron confinement characteristics, which can increase the potential barrier for carrier transport, enhance the coupling strength between the carriers and the surrounding Type I quantum dots, and improve the transport speed of the carriers.

[0043] Specifically, the energy level schematic diagram of Type I quantum dots is as shown in Figure 5 When the composite material contains Type I quantum dots and Type II quantum dots, its energy level schematic diagram is as shown in Figure 6 or Figure 7 When the composite material contains Type I quantum dots and inverse Type I quantum dots, its energy level schematic diagram is as shown in Figure 8 When the composite material contains Type I quantum dots, Type II quantum dots and inverse Type I quantum dots, its energy level schematic diagram is as shown in Figure 9 or Figure 10 It should be noted that Figures 5 to 10 in, the upper part is the conduction band energy level, and the lower part is the valence band energy level.

[0044] In some embodiments, the mass ratio of the first core-shell quantum dot to the second core-shell quantum dot is [95, 100):(0, 5], for example, it can be 95.5:4.5, 96:4, 96.5:3.5, 97:3, 97.5:2.5, 98:2, 98.5:1.5, 99:1, 99.5:0.5, etc. Within the range of the mass ratio, the first core-shell quantum dot can ensure its high fluorescence quantum yield and stability, and the second core-shell quantum dot can effectively adjust the balance of carrier injection and transport.

[0045] It should be noted that the symbol (a, b) represents all real numbers between real number a and real number b, but does not include a and b, which is equivalent to the number set {x|a < x < b}, denoted as (a, b), and the values do not include a and b. The symbol [a, b] represents all real numbers between real number a and real number b, including a and b. It is equivalent to the number set {x|a ≤ x ≤ b}, denoted as [a, b], and the values include a and b. Correspondingly, [95, 100) represents the number set {x|95 ≤ x < 100}, including 95 but not including 100, and (0, 5] represents the number set {x|0 < x ≤ 5}, not including 0 but including 5. In some embodiments, in the composite material, the second core-shell quantum dots are uniformly distributed in the first core-shell quantum dots.

[0046] In some embodiments, the absolute value of the difference between the average particle size of the first core-shell quantum dots and the average particle size of the second core-shell quantum dots is less than or equal to 2 nm. For example, it can be 0 nm, 0.2 nm, 0.5 nm, 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, 1.8 nm, etc. Within the range of the absolute value of the difference, it can be ensured that the second core-shell quantum dots in the composite material are uniformly distributed in the first core-shell quantum dots.

[0047] In some embodiments, when the second core-shell quantum dots include Type II quantum dots and inverse Type I quantum dots, the absolute value of the difference between the average particle size of the Type II quantum dots and the average particle size of the inverse Type I quantum dots is less than or equal to 4 nm.

[0048] Preferably, the absolute value of the difference between the average particle size of the Type II quantum dots and the average particle size of the inverse Type I quantum dots is less than or equal to 2 nm.

[0049] In some embodiments, the average particle size of the first core-shell quantum dots is 5 nm to 15 nm. For example, it can be 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, etc.

[0050] Furthermore, the average particle size of the Type I quantum dots is 5 nm to 15 nm. For example, it can be 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, etc.

[0051] In some embodiments, the average particle size of the second core-shell quantum dots is 5 nm to 15 nm. For example, it can be 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, etc.

[0052] Further, the average particle size of the Type II quantum dots is 5 nm to 15 nm, and for example, it can be 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, etc.

[0053] The average particle size of the inverse Type I quantum dots is 5 nm to 15 nm, and for example, it can be 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, etc.

[0054] In some embodiments, the Type I quantum dots include a first core and a first ligand connected to the outer surface of its shell layer.

[0055] In some embodiments, the Type II quantum dots include a second core and a second ligand connected to the outer surface of its shell layer.

[0056] In some embodiments, the inverse Type I quantum dots include a third core and a third ligand connected to the outer surface of its shell layer.

[0057] In some embodiments, the first ligand contains a first active functional group.

[0058] Further, the first active functional group includes one or more of a mercapto group, a carboxyl group, a halogen, an amino group, and a phosphino group.

[0059] In some embodiments, the first ligand includes one or more of an acid ligand, an amine ligand, a thiol ligand, a phosphine ligand, an ammonium ligand, and a halogen ligand; the acid ligand includes one or more of oleic acid and 3-mercaptopropionic acid, the amine ligand includes one or more of octylamine, oleylamine, and 1,2-ethylenediamine, the thiol ligand includes one or more of propanethiol, butanethiol, octanethiol, dodecanethiol, benzenethiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, and 1,2-ethanedithiol, the phosphine ligand includes one or more of tri-n-octylphosphine, tri-n-octylphosphine oxide, and tributylphosphine, the ammonium ligand includes ammonium thiocyanate, and the halogen includes one or more of fluorine, chlorine, bromine, and iodine.

[0060] In some embodiments, in the Type I quantum dots, the mass fraction of the first ligand is 8% to 40%, and for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, etc.

[0061] In some embodiments, the second ligand contains a second active functional group.

[0062] Further, the second active functional group includes one or more of a mercapto group, a carboxyl group, a halogen, an amino group, and a phosphino group.

[0063] In some embodiments, the second ligand includes one or more of an acid ligand, an amine ligand, a thiol ligand, a phosphine ligand, an ammonium ligand, and a halogen ligand; the acid ligand includes one or more of oleic acid and 3-mercaptopropionic acid, the amine ligand includes one or more of octylamine, oleylamine, and 1,2-ethylenediamine, the thiol ligand includes one or more of propanethiol, butanethiol, octanethiol, dodecanethiol, benzenethiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, and 1,2-ethanedithiol, the phosphine ligand includes one or more of tri-n-octylphosphine, tri-n-octylphosphine oxide, and tributylphosphine, the ammonium ligand includes ammonium thiocyanate, and the halogen includes one or more of fluorine, chlorine, bromine, and iodine.

[0064] In some embodiments, in the Type II quantum dots, the mass fraction of the second ligand is 8% to 40%, and for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, etc.

[0065] In some embodiments, the third ligand contains a third active functional group.

[0066] Furthermore, the third active functional group includes one or more of a thiol group, a carboxyl group, a halogen, an amino group, and a phosphino group.

[0067] In some embodiments, the third ligand includes one or more of an acid ligand, an amine ligand, a thiol ligand, a phosphine ligand, an ammonium ligand, and a halogen ligand; the acid ligand includes one or more of oleic acid and 3-mercaptopropionic acid, the amine ligand includes one or more of octylamine, oleylamine, and 1,2-ethylenediamine, the thiol ligand includes one or more of propanethiol, butanethiol, octanethiol, dodecanethiol, benzenethiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, and 1,2-ethanedithiol, the phosphine ligand includes one or more of tri-n-octylphosphine, tri-n-octylphosphine oxide, and tributylphosphine, the ammonium ligand includes ammonium thiocyanate, and the halogen includes one or more of fluorine, chlorine, bromine, and iodine.

[0068] In some embodiments, in the inverse Type I quantum dots, the mass fraction of the third ligand is 8% to 40%, and for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, etc.

[0069] In some embodiments, the materials of the first core, the second core, and the third core are the same. Thus, the first core-shell quantum dots and the second core-shell quantum dots can be dispersed in the same solvent.

[0070] In some embodiments, the first ligand, the second ligand, and the third ligand are the same.

[0071] In some embodiments, the absolute value of the difference between any two of the mass fractions of the first ligand, the mass fraction of the second ligand, and the mass fraction of the third ligand is less than or equal to 5%, and can be, for example, 0, 1%, 2%, 3%, 4%, etc.

[0072] In this way, the compatibility of the Type I quantum dots, the Type II quantum dots, and the inverse Type I quantum dots can be ensured.

[0073] In some embodiments, the material of the Type I quantum dots includes one or more of CdZnSe / CdZnS / ZnS, CdSe / ZnS, CdSe / CdS / ZnS, CdSe / ZnSe / ZnS, CdS / ZnS, CdSe / ZnSe, CdSe / CdS, CdSeS / ZnSe.

[0074] In some embodiments, the material of the Type II quantum dots includes one or more of CdZnSe / ZnSe, CdSe / ZnTe, CdTe / CdSe, ZnTe / CdSe.

[0075] In some embodiments, the material of the inverse Type I quantum dots includes one or more of CdZnSe / CdSe, ZnSe / CdSe, CdZnSe / CdSeS, CdSeS / CdSe, CdZnSeS / CdS, CdZnSeS / CdSeS, CdZnSeS / CdZnSe, CdZnSeS / CdS, ZnSeS / CdS, ZnSeS / CdZnS, ZnSeS / CdSe, ZnSeS / CdZnSe, CdZnSeS / CdSe.

[0076] It should be noted that the material before " / " represents the core layer material, and the material after " / " represents the shell layer material. For example, CdSe / ZnS means that the core material is CdSe, and the shell material wrapping the core material is ZnS; CdZnSe / CdZnS / ZnS means that the core material is CdZnSe, the first shell material wrapping the core material is CdZnS, and the second shell material wrapping the first shell material is ZnS.

[0077] In a second aspect, an embodiment of the present application provides an ink, which includes the above composite material and a solvent.

[0078] Please refer to Figure 11 , an embodiment of the present application provides a method for preparing an ink, including:

[0079] S11. Provide a first core-shell quantum dot and a second core-shell quantum dot, where the first core-shell quantum dot includes a Type I quantum dot, and the second core-shell quantum dot includes one or more of a Type II quantum dot and an inverse Type I quantum dot;

[0080] S12. Provide a solvent, and mix the solvent with the first core-shell quantum dot and the second core-shell quantum dot to obtain an ink.

[0081] It can be understood that the Type I quantum dot, the Type II quantum dot, and the inverse Type I quantum dot can be obtained by growing different types of shell layers on the same quantum dot core. The synthesis systems of the Type I quantum dot, the Type II quantum dot, and the inverse Type I quantum dot are the same, which can ensure that the types of surface ligands are the same and the contents are close, enabling the Type I quantum dot, the Type II quantum dot, and the inverse Type I quantum dot to be soluble in the same solvent, promoting their compatibility, and optimizing the synthesis steps of the Type I quantum dot, the Type II quantum dot, and the inverse Type I quantum dot.

[0082] The synthesis methods of the Type I quantum dot, the Type II quantum dot, and the inverse Type I quantum dot can adopt the conventional synthesis methods of core-shell quantum dots in the art, such as the precursor high-temperature injection method, the alternating ion layer adsorption and growth method, the single precursor method, the seed growth method, the ion exchange method, the one-pot method, the microwave synthesis method, etc.

[0083] In some embodiments, the solvent includes one or more of chlorobenzene, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, pyrrole, butyric acid, and cresol.

[0084] In some embodiments, in the ink, the sum of the mass concentrations of the first core-shell quantum dot and the second core-shell quantum dot is 10 mg / mL to 100 mg / mL, and can be, for example, 20 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL, 70 mg / mL, 80 mg / mL, 90 mg / mL, etc. Within the range of the mass concentration, it is beneficial to the sufficient and uniform dissolution of the first core-shell quantum dot and the second core-shell quantum dot. It can be understood that the sum of the mass concentrations of the first core-shell quantum dot and the second core-shell quantum dot refers to the ratio of the sum of the masses of the first core-shell quantum dot and the second core-shell quantum dot to the volume of the quantum dot solution.

[0085] In some embodiments, in the ink, the mass ratio of the first core-shell quantum dots to the second core-shell quantum dots is [95, 100):(0, 5], and for example, it can be 95.5:4.5, 96:4, 96.5:3.5, 97:3, 97.5:2.5, 98:2, 98.5:1.5, 99:1, 99.5:0.5, etc.

[0086] In a third aspect, please refer to Figure 12 , an embodiment of the present application provides a thin film 11, and the material of the thin film 11 includes the above composite material.

[0087] The preparation method of the thin film 11 can adopt conventional techniques in the art, such as chemical methods or physical methods. Among them, chemical methods include chemical vapor deposition method, sequential ionic layer adsorption and reaction method, anodic oxidation method, electrolytic deposition method, coprecipitation method. Physical methods include physical coating method and solution method. Among them, physical coating methods include: thermal evaporation coating method, electron beam evaporation coating method, magnetron sputtering method, multi-arc ion coating method, physical vapor deposition method, atomic layer deposition method, pulsed laser deposition method, etc.; the solution method can be spin coating method, printing method, inkjet printing method, blade coating method, printing method, dip coating method, immersion method, spraying method, roll coating method, casting method, slot die coating method, bar coating method, etc.

[0088] In some embodiments, the thin film 11 is prepared by spin coating the above ink.

[0089] In some embodiments, the thickness of the thin film 11 is 5 nm to 100 nm, and for example, it can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, etc.

[0090] In a fourth aspect, please refer to Figure 13 , an embodiment of the present application further provides an optoelectronic device, including a first electrode 20, a photoactive layer 10, and a second electrode 30 which are sequentially stacked, and the material of the photoactive layer 10 includes the above composite material.

[0091] It should be noted that when there is an excess of electrons in the optoelectronic device, it is suitable to add Type II quantum dots with electron confinement and hole non-confinement; when there is an excess of holes in the optoelectronic device, it is suitable to add Type II quantum dots with electron non-confinement and hole confinement; when the holes and electrons in the optoelectronic device are relatively balanced, it is suitable to add inverse type I quantum dots.

[0092] In some embodiments, the optoelectronic device includes a light-emitting diode.

[0093] In some embodiments, the optoelectronic device is a normal-type optoelectronic device.

[0094] In some other embodiments, the optoelectronic device is an inverted optoelectronic device.

[0095] In some embodiments, referring to Figure 14 , the optoelectronic device further includes one or more of a first carrier functional layer 40 and a second carrier functional layer 50. The first carrier functional layer 40 is disposed between the first electrode 20 and the photoactive layer 10, and the second carrier functional layer 50 is disposed between the photoactive layer 10 and the second electrode 30.

[0096] In some embodiments, the first carrier functional layer 40 is a hole functional layer, and the second carrier functional layer 50 is an electron functional layer. Correspondingly, the first electrode 20 is an anode, and the second electrode 30 is a cathode.

[0097] In some other embodiments, the second carrier functional layer 50 is a hole functional layer, and the first carrier functional layer 40 is an electron functional layer. Correspondingly, the second electrode 30 is an anode, and the first electrode 20 is a cathode.

[0098] Further, the hole functional layer includes one or more of a hole injection layer and a hole transport layer.

[0099] The electron functional layer includes one or more of an electron injection layer and an electron transport layer.

[0100] In some embodiments, the first electrode 20 and the second electrode 30 each independently include one or more of a metal, a carbon material, and a metal oxide; the metal includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon material includes one or more of graphite, carbon nanotubes, graphene, and carbon fiber; the metal oxide includes a metal oxide electrode or a composite electrode with a metal sandwiched between doped or undoped transparent metal oxides. The material of the metal oxide electrode includes one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO3, and AMO, and the composite electrode includes 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. Herein, " / " represents a stacked structure. For example, AZO / Ag / AZO represents a composite electrode including a sequentially stacked AZO layer, an Ag layer, and an AZO layer.

[0101] In some embodiments, the material of the hole functional layer includes one or more of 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(carbazol-9-yl)triphenylamine, trichloroisocyanuric acid, terbium-doped phosphate-based green luminescent material, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), poly[bis(4-phenyl)(4-butylphenyl)amine], polyaniline, polypyrrole, poly(p-phenylene vinylene), poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], copper phthalocyanine, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT, PEDOT:PSS and its derivatives, PEDOT:PSS derivatives doped with s-MoO3, poly(N-vinylcarbazole) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-bis(naphthalen-1-yl)-N,N'-diphenylbenzidine, spiro-NPB, nanocrystalline diamond, microcrystalline cellulose and tetracyanoquinodimethane, doped graphene, undoped graphene, second doped metal oxide particles, second undoped metal oxide particles, metal sulfides, metal selenides and metal nitrides. The metal oxides in the second doped metal oxide particles and the metal oxides in the second undoped metal oxide particles independently include one or more of MoO3, WO3, NiO, CrO3, CuO, Cu2O, V2O5. The doping elements in the second doped metal oxide particles include one or more of Mo, W, Ni, Cr, Cu, V. The metal sulfides include one or more of CuS, MoS3, WS3. The metal selenides include one or more of MoSe3, WSe3. The metal nitrides include p-type gallium nitride.

[0102] In some embodiments, the material of the electronic functional layer includes one or more of first doped metal oxide particles, first undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The material of the first undoped metal oxide particles includes one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxides in the first doped metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping elements in the first doped metal oxide particles include one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The IIB-VIA group semiconductor materials include one or more of ZnS, ZnSe, and CdS. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS.

[0103] Fourthly, an embodiment of the present application further provides a display device, and the display device includes the above optoelectronic device.

[0104] The display device can be any electronic product with a display function. The electronic products include but are not limited to smart phones, tablet computers, laptop computers, digital cameras, digital video cameras, smart wearable devices, smart weighing electronic scales, in-vehicle displays, televisions, or e-book readers. Among them, the smart wearable devices can be, for example, smart bracelets, smart watches, virtual reality (VR) helmets, etc.

[0105] The present application will be specifically described below through specific embodiments. The following embodiments are only partial embodiments of the present application and do not limit the present application.

[0106] Embodiment 1

[0107] This embodiment provides a quantum dot film. The material of the quantum dot film includes Type I quantum dots and Type II quantum dots. The Type I quantum dots include CdZnSe / CdZnS / ZnS, and the ligands are 20% oleic acid and oleylamine. The average particle size is about 14 nm, and the band gap is 2 eV. The Type II quantum dots include CdZnSe / ZnSe, and the ligands are 18% oleic acid and oleylamine. The average particle size is about 15 nm, and the band gap is 2.2 eV. The preparation method of the quantum dot film is as follows:

[0108] Prepare a quantum dot solution, which includes Type I quantum dots CdZnSe / CdZnS / ZnS and Type II quantum dots CdZnSe / ZnSe. The mass ratio of Type I quantum dots CdZnSe / CdZnS / ZnS to Type II quantum dots CdZnSe / ZnSe is 97:3. Set the quantum dot solution on a substrate to obtain a quantum dot thin film.

[0109] Example 2

[0110] This example is basically the same as Example 1, except that in this example, Type II quantum dots CdZnSe / ZnSe are replaced with inverse Type I quantum dots CdZnSe / CdSe. The ligands of CdZnSe / CdSe are oleic acid and oleylamine, the average particle size is about 13 nm, and the band gap is 1.96 eV. Among them, the mass ratio of Type I quantum dots CdZnSe / CdZnS / ZnS to inverse Type I quantum dots CdZnSe / CdSe is 97:3.

[0111] Example 3

[0112] This example is basically the same as Example 1, except that in this example, the material of the quantum dot thin film further includes inverse Type I quantum dots CdZnSe / CdSe. The ligands of CdZnSe / CdSe are oleic acid and oleylamine, the particle size is about 13 nm, and the band gap is 1.96 eV. Among them, the mass ratio of Type I quantum dots CdZnSe / CdZnS / ZnS, Type II quantum dots CdZnSe / ZnSe to inverse Type I quantum dots CdZnSe / CdSe is 97:1.5:1.5.

[0113] Example 4

[0114] This example is basically the same as Example 1, except that in this example, the mass ratio of Type I quantum dots CdZnSe / CdZnS / ZnS to Type II quantum dots CdZnSe / ZnSe is 99.9:0.1.

[0115] Example 5

[0116] This example is basically the same as Example 1, except that in this example, the mass ratio of Type I quantum dots CdZnSe / CdZnS / ZnS to Type II quantum dots CdZnSe / ZnSe is 95:5.

[0117] Example 6

[0118] This embodiment is basically the same as Embodiment 2, except that in this embodiment, the mass ratio of Type I quantum dots CdZnSe / CdZnS / ZnS to inverse Type I quantum dots CdZnSe / CdSe is 99.9:0.1.

[0119] Embodiment 7

[0120] This embodiment is basically the same as Embodiment 2, except that in this embodiment, the mass ratio of Type I quantum dots CdZnSe / CdZnS / ZnS to inverse Type I quantum dots CdZnSe / CdSe is 95:5.

[0121] Embodiment 8

[0122] This embodiment is basically the same as Embodiment 3, except that in this embodiment, the mass ratio of Type I quantum dots CdZnSe / CdZnS / ZnS, Type II quantum dots CdZnSe / ZnSe to inverse Type I quantum dots CdZnSe / CdSe is 97:2:1.

[0123] Embodiment 9

[0124] This embodiment is basically the same as Embodiment 3, except that in this embodiment, the mass ratio of Type I quantum dots CdZnSe / CdZnS / ZnS, Type II quantum dots CdZnSe / ZnSe to inverse Type I quantum dots CdZnSe / CdSe is 97:1:2.

[0125] Embodiment 10

[0126] This embodiment is basically the same as Embodiment 1, except that in this embodiment, Type I quantum dots CdZnSe / ZnSe / ZnS are replaced with CdSe / ZnSe / ZnS, and Type II quantum dots CdZnSe / ZnSe are replaced with CdSe / ZnTe.

[0127] Embodiment 11

[0128] This embodiment is basically the same as Embodiment 2, except that in this embodiment, Type I quantum dots CdZnSe / ZnSe / ZnS are replaced with CdSe / ZnSe / ZnS, and inverse Type I quantum dots CdZnSe / CdSe are replaced with CdZnSeS / CdSe.

[0129] Embodiment 12

[0130] This example is basically the same as Example 3, except that in this example, the Type I quantum dots CdZnSe / ZnSe / ZnS are replaced by CdSe / ZnSe / ZnS, the Type II quantum dots CdZnSe / ZnSe are replaced by CdSe / ZnTe, and the inverse Type I quantum dots CdZnSe / CdSe are replaced by CdZnSe / CdSeS.

[0131] Comparative Example 1

[0132] This comparative example is basically the same as Example 1, except that in this comparative example, the material of the quantum dot thin film does not contain the Type II quantum dots CdZnSe / ZnSe.

[0133] Comparative Example 2

[0134] This comparative example is basically the same as Example 1, except that in this comparative example, the material of the quantum dot thin film does not contain the Type I quantum dots CdZnSe / CdZnS / ZnS.

[0135] Comparative Example 3

[0136] This comparative example is basically the same as Example 2, except that in this comparative example, the material of the quantum dot thin film does not contain the Type I quantum dots CdZnSe / CdZnS / ZnS.

[0137] Comparative Example 4

[0138] This comparative example is basically the same as Example 3, except that in this comparative example, the material of the quantum dot thin film does not contain the Type I quantum dots CdZnSe / CdZnS / ZnS, and the mass ratio of the Type II quantum dots CdZnSe / ZnSe to the inverse Type I quantum dots CdZnSe / CdSe is 50:50.

[0139] Comparative Example 5

[0140] This comparative example is basically the same as Example 1, except that in this comparative example, the mass ratio of the Type I quantum dots CdZnSe / CdZnS / ZnS to the Type II quantum dots CdZnSe / ZnSe is 92:8.

[0141] Comparative Example 6

[0142] This comparative example is basically the same as Example 1, except that in this comparative example, the average particle size of the Type II quantum dots CdZnSe / ZnSe is about 19 nm.

[0143] Comparative Example 7

[0144] This comparative example is basically the same as Example 1, except that in this comparative example, the ligand of the Type II quantum dots is 28% oleic acid and oleylamine.

[0145] The exciton fluorescence lifetimes of the quantum dot films in Test Examples 1 to 12 and Comparative Examples 1 to 7 were measured, and the exciton fluorescence lifetime curves of the quantum dot films provided in Example 1 and Comparative Example 1 are as follows Figure 15 shown. The exciton fluorescence lifetimes (τ, unit: ns) of the quantum dot films in Examples 1 to 12 and Comparative Examples 1 to 7 are shown in Table 1. Among them, the exciton fluorescence lifetime refers to the time of quantum dot fluorescence emission, that is, the time interval from excitation to de-excitation, and is measured using a fluorescence lifetime measuring instrument.

[0146] Table 1

[0147]

[0148]

[0149] From Figure 15 and Table 1, it can be seen that:

[0150] From Examples 1 to 3 and Comparative Examples 1 to 4, it can be obtained that when Type I quantum dots, Type II quantum dots, and inverse Type I quantum dots are used separately as the materials of the quantum dot film, the fluorescence lifetime of the Type I quantum dot film is relatively long, and the fluorescence lifetime of the inverse Type I quantum dot film is relatively the worst. The fluorescence lifetime of the film after mixing Type II quantum dots and inverse Type I quantum dots is improved compared with that of a single quantum dot, but it is also worse than that of the Type I quantum dot film. And doping Type II quantum dots and / or inverse Type I quantum dots into Type I quantum dots can effectively improve the fluorescence lifetime of the quantum dot film. Among them, the effect is the best when doping inverse Type I quantum dots;

[0151] From Example 1, Examples 4 to 9 and Comparative Example 1, Comparative Example 5, it can be obtained that in the mixed quantum dot film, the proportion of various types of quantum dots has a great influence on the fluorescence lifetime of the quantum dot film. Excessive doping of quantum dots will affect the normal performance of Type I quantum dots and thus affect the fluorescence lifetime of the quantum dot film; when doping Type II quantum dots and / or inverse Type I quantum dots at the same time, the effect on the fluorescence lifetime is relatively better when the amount of inverse Type I quantum dots is greater than that of Type II quantum dots;

[0152] From Example 1, Examples 10 to 12 and Comparative Example 1, it can be obtained that different quantum dot materials have a certain influence on the fluorescence lifetime of the quantum dot film, which is determined by the self-performance of the quantum dot materials. When the core layer materials of various types of quantum dots are the same, the fluorescence lifetime of the quantum dot film is better than when the core layer materials are different;

[0153] It can be seen from Example 1 and Comparative Examples 6-7 that when the particle sizes of Type I quantum dots and Type II quantum dots and / or inverse Type I quantum dots differ significantly, or when their surface ligand contents differ significantly, the compatibility of the quantum dots decreases, which will have an adverse effect on the fluorescence lifetime of the quantum dot film.

[0154] Device Example 1

[0155] This device example provides an optoelectronic device, and the preparation method is as follows:

[0156] Provide ITO glass, dip a cotton swab in a small amount of soapy water and wipe the ITO surface to remove visible impurities on the surface. Then, ultrasonically clean it with deionized water, acetone, ethanol, and isopropanol for 15 min, and then dry it with nitrogen and irradiate it with UV for 15 min to form an ITO anode;

[0157] Spin-coat PEDOT:PSS on the ITO anode at a spinning speed of 5000 rpm for 30 s, and then heat it at 100 °C for 15 min to form a hole injection layer;

[0158] Dissolve TFB in chlorobenzene at a concentration of 8 mg / mL, spin-coat it on the hole injection layer at a spinning speed of 3000 rpm for 30 s, and then heat it at 100 °C for 15 min to form a hole transport layer;

[0159] Set the quantum dot film of Example 1 on the hole transport layer, spin-coat an ethanol solution of ZnO on the quantum dot film at a spinning speed of 4000 rpm, and then heat it at 80 °C for 10 min to form an electron transport layer;

[0160] On the electron transport layer, turn on the Ag target, and the Ag target is evaporated at at a rate to form a cathode;

[0161] Encapsulate to obtain the optoelectronic device.

[0162] Device Examples 2-12

[0163] Device Examples 2-12 are basically the same as Device Example 1, except that the quantum dot films of Examples 2-12 are respectively used to replace the quantum dot film of Example 1 to obtain the optoelectronic device.

[0164] Device Comparative Examples 1-7

[0165] Device Comparative Examples 1-7 are basically the same as Device Example 1, except that the quantum dot films of Comparative Examples 1-7 are respectively used to replace the quantum dot film of Example 1 to obtain the optoelectronic device.

[0166] The external quantum efficiency EQE (%) and the lifetime T95@1k nit of the optoelectronic devices of Device Examples 1 to 12 and Device Comparative Examples 1 to 7 were tested, and the test results are shown in Table 2.

[0167] Among them, the test method for the external quantum efficiency EQE is as follows: the ratio of the number of electron-hole pairs injected into the quantum dots to the number of emitted photons, with the unit of %, is an important parameter to measure the quality of electro-optical devices, and it can be obtained by measuring with an EQE optical test instrument. The specific calculation formula is as follows:

[0168]

[0169] Among them, ηe is the optical output coupling efficiency, ηr is the ratio of the number of recombined carriers to the number of injected carriers, χ is the ratio of the number of excitons generating photons to the total number of excitons, K R is the rate of the radiative process, K NR is the rate of the non-radiative process. Test conditions: carried out at room temperature, and the air humidity is 30 - 60%.

[0170] The test method for the lifetime T95@1000nit is as follows: the time required for the device to reduce the brightness to a certain proportion of the maximum brightness under a constant current or voltage drive. The time when the brightness drops to 95% of the maximum brightness is defined as T95, and this lifetime is the measured lifetime. To shorten the test cycle, the device lifetime test is usually carried out by accelerating the device aging at high brightness, and the lifetime at high brightness is obtained by fitting with an extended exponential decay brightness decay fitting formula. For example, the lifetime at 1000nit is denoted as T95@1k nit. The specific calculation formula is as follows:

[0171]

[0172] Among them, T95L is the lifetime at low brightness, T95 H is the measured lifetime at high brightness, L H is the device accelerated to the maximum brightness, L L is 1000nit, A is the acceleration factor, and in this experiment, the A value is obtained as 1.7 by measuring the lifetimes of several groups of red QLED devices at the rated brightness.

[0173] Table 2

[0174]

[0175]

[0176] As can be seen from Table 2:

[0177] It can be obtained from Device Examples 1 to 3 and Device Comparative Examples 1 to 4 that when Type I quantum dots, Type II quantum dots, and inverse Type I quantum dots are used separately as the materials of the light-emitting layer, the performances of the optoelectronic devices based on Type I quantum dots and those based on Type II quantum dots are not much different, while the performance of the optoelectronic device based on inverse Type I quantum dots is relatively the worst. However, doping Type II quantum dots and / or inverse Type I quantum dots into Type I quantum dots can effectively improve the external quantum efficiency and service life of the optoelectronic device;

[0178] It can be obtained from Device Example 1, Device Examples 4 to 9, and Device Comparative Example 1, Device Comparative Example 5 that in the mixed quantum dots, the proportion of various types of quantum dots has a great influence on the optoelectronic device. If the dosage of the doped quantum dots is too large, it will affect the normal performance of Type I quantum dots and then cause the performance of the optoelectronic device to decline; when doping Type II quantum dots and / or inverse Type I quantum dots simultaneously, the relationship between the dosage of inverse Type I quantum dots and that of Type II quantum dots has no significant influence on the external quantum efficiency and service life of the optoelectronic device;

[0179] It can be obtained from Device Example 1, Device Examples 10 to 12, and Device Comparative Example 1 that different quantum dot materials have a certain influence on the fluorescence lifetime of the quantum dot film, which is determined by the inherent properties of the quantum dot materials. However, compared with Device Comparative Example 1, both the external quantum efficiency and the service life are improved. When the core layer materials of various quantum dots are the same, the performance improvement of the optoelectronic device is the most obvious;

[0180] It can be obtained from Device Example 1 and Device Comparative Example 6 that when the particle sizes of Type I quantum dots and Type II quantum dots and / or inverse Type I quantum dots are quite different, the compatibility of the quantum dots decreases, affecting the performance of the quantum dot film, and then causing the decline of both the external quantum efficiency and the service life of the optoelectronic device.

[0181] The composite material, ink, film, and optoelectronic device provided by the embodiments of the present application have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A composite material, characterized in that, It includes a first core-shell quantum dot and a second core-shell quantum dot. The first core-shell quantum dot includes a Type I quantum dot, and the second core-shell quantum dot includes one or more of a Type II quantum dot and an inverse Type I quantum dot.

2. The composite material according to claim 1, wherein the mass ratio of the first core-shell quantum dot to the second core-shell quantum dot is [95, 100):(0, 5]; and / or the absolute value of the difference between the average particle size of the first core-shell quantum dot and the average particle size of the second core-shell quantum dot is less than or equal to 2 nm; and / or the average particle size of the first core-shell quantum dot is 5 nm to 15 nm; and / or the average particle size of the second core-shell quantum dot is 5 nm to 15 nm.

3. The composite material according to claim 1, wherein the Type I quantum dot includes a first inner core and a first ligand connected to the outer surface of its shell layer; the Type II quantum dot includes a second inner core and a second ligand connected to the outer surface of its shell layer; the inverse Type I quantum dot includes a third inner core and a third ligand connected to the outer surface of its shell layer; Optionally, each of the first ligand, the second ligand, and the third ligand independently includes one or more of an acid ligand, an amine ligand, a thiol ligand, a phosphine ligand, an ammonium ligand, and a halogen ligand; preferably, the acid ligand includes one or more of oleic acid and 3-mercaptopropionic acid, the amine ligand includes one or more of octylamine, oleylamine, and 1,2-ethylenediamine, the thiol ligand includes one or more of propanethiol, butanethiol, octanethiol, dodecanethiol, benzenethiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, and 1,2-ethanedithiol, the phosphine ligand includes one or more of tri-n-octylphosphine, tri-n-octylphosphine oxide, and tri-butylphosphine, the ammonium ligand includes ammonium thiocyanate, and the halogen includes one or more of fluorine, chlorine, bromine, and iodine; Optionally, in the Type I quantum dot, the mass fraction of the first ligand is 8% to 40%; Optionally, in the Type II quantum dot, the mass fraction of the second ligand is 8% to 40%; Optionally, in the inverse Type I quantum dot, the mass fraction of the third ligand is 8% to 40%; Optionally, the materials of the first inner core, the second inner core, and the third inner core are the same; Optionally, the first ligand, the second ligand, and the third ligand are the same; Optionally, the absolute value of the difference between any two of the mass fractions of the first ligand, the mass fraction of the second ligand, and the mass fraction of the third ligand is less than or equal to 5%.

4. The composite material according to claim 1, wherein the material of the Type I quantum dot includes one or more of CdZnSe / CdZnS / ZnS, CdSe / ZnS, CdSe / CdS / ZnS, CdSe / ZnSe / ZnS, CdS / ZnS, CdSe / ZnSe, CdSe / CdS, and CdSeS / ZnSe; and / or The material of the Type II quantum dots includes one or more of CdZnSe / ZnSe, CdSe / ZnTe, CdTe / CdSe, ZnTe / CdSe; and / or The material of the inverse Type I quantum dots includes one or more of CdZnSe / CdSe, ZnSe / CdSe, CdZnSe / CdSeS, CdSeS / CdSe, CdZnSeS / CdS, CdZnSeS / CdSeS, CdZnSeS / CdZnSe, CdZnSeS / CdS, ZnSeS / CdS, ZnSeS / CdZnS, ZnSeS / CdSe, ZnSeS / CdZnSe, CdZnSeS / CdSe.

5. An ink, characterized in that, It includes a first core-shell quantum dot, a second core-shell quantum dot and a solvent, wherein the first core-shell quantum dot includes Type I quantum dots, and the second core-shell quantum dot includes one or more of Type II quantum dots and inverse Type I quantum dots.

6. The ink according to claim 5, wherein The solvent includes one or more of chlorobenzene, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, pyrrole, butyric acid, cresol; and / or In the ink, the sum of the mass concentrations of the first core-shell quantum dot and the second core-shell quantum dot is 10 mg / mL to 100 mg / mL; and / or In the ink, the mass ratio of the first core-shell quantum dot to the second core-shell quantum dot is [95, 100):(0, 5].[[]END]] 7. A thin film, characterized in that, The material of the thin film includes a first core-shell quantum dot and a second core-shell quantum dot, wherein the first core-shell quantum dot includes Type I quantum dots, and the second core-shell quantum dot includes one or more of Type II quantum dots and inverse Type I quantum dots.

8. The thin film according to claim 7, wherein The mass ratio of the first core-shell quantum dot to the second core-shell quantum dot is [95, 100):(0, 5]; and / or The absolute value of the difference between the average particle size of the first core-shell quantum dot and the average particle size of the second core-shell quantum dot is less than or equal to 2 nm; and / or The average particle size of the first core-shell quantum dot is 5 nm to 15 nm; and / or The average particle size of the second core-shell quantum dot is 5 nm to 15 nm.

9. The thin film according to claim 7, wherein The Type I quantum dots include a first inner core and a first ligand connected to the outer surface of its shell layer; the Type II quantum dots include a second inner core and a second ligand connected to the outer surface of its shell layer; the inverse Type I quantum dots include a third inner core and a third ligand connected to the outer surface of its shell layer; Optionally, each of the first ligand, the second ligand, and the third ligand independently includes one or more of an acid ligand, an amine ligand, a thiol ligand, a phosphine ligand, an ammonium ligand, and a halogen ligand; preferably, the acid ligand includes one or more of oleic acid and 3-mercaptopropionic acid, the amine ligand includes one or more of octylamine, oleylamine, and 1,2-ethylenediamine, the thiol ligand includes one or more of propanethiol, butanethiol, octanethiol, dodecanethiol, benzenethiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, and 1,2-ethanedithiol, the phosphine ligand includes one or more of tri-n-octylphosphine, tri-n-octylphosphine oxide, and tributylphosphine, the ammonium ligand includes ammonium thiocyanate, and the halogen includes one or more of fluorine, chlorine, bromine, and iodine; Optionally, in the Type I quantum dots, the mass fraction of the first ligand is 8% to 40%; Optionally, in the Type II quantum dots, the mass fraction of the second ligand is 8% to 40%; Optionally, in the inverse Type I quantum dots, the mass fraction of the third ligand is 8% to 40%; Optionally, the materials of the first core, the second core, and the third core are the same; Optionally, the first ligand, the second ligand, and the third ligand are the same; Optionally, the absolute value of the difference between any two of the mass fractions of the first ligand, the mass fraction of the second ligand, and the mass fraction of the third ligand is less than or equal to 5%; 10. An optoelectronic device, the optoelectronic device comprising a first electrode, a photoactive layer, and a second electrode that are sequentially stacked, characterized in that, The material of the photoactive layer includes the composite material according to any one of claims 1 to 4.

11. The optoelectronic device according to claim 10, wherein, The optoelectronic device further includes one or more of a first carrier functional layer and a second carrier functional layer. The first carrier functional layer is disposed between the first electrode and the photoactive layer, and the second carrier functional layer is disposed between the photoactive layer and the second electrode; the first carrier functional layer is a hole functional layer, and the second carrier functional layer is an electron functional layer; or the second carrier functional layer is a hole functional layer, and the first carrier functional layer is an electron functional layer; Optionally, each of the first electrode and the second electrode independently includes one or more of a metal, a carbon material, and a metal oxide; the metal includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon material includes one or more of graphite, carbon nanotubes, graphene, and carbon fibers; the metal oxide includes a metal oxide electrode or a composite electrode having a metal disposed between doped or undoped transparent metal oxides, the material of the metal oxide electrode includes one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO3, and AMO, and the composite electrode includes 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; Optionally, the material of the hole functional layer includes one or more of 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(carbazol-9-yl)triphenylamine, trichloroisocyanuric acid, terbium-doped phosphate-based green luminescent material, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), poly[bis(4-phenyl)(4-butylphenyl)amine], polyaniline, polypyrrole, poly(p-phenylene vinylene), poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], copper phthalocyanine, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT, PEDOT:PSS and its derivatives, PEDOT:PSS derivatives doped with s-MoO3, poly(N-vinylcarbazole) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-bis(naphthalen-1-yl)-N,N'-diphenylbenzidine, spiro-NPB, nanocrystalline diamond, microcrystalline cellulose and tetracyanoquinodimethane, doped graphene, undoped graphene, second doped metal oxide particles, second undoped metal oxide particles, metal sulfides, metal selenides and metal nitrides, wherein the metal oxides in the second doped metal oxide particles and the metal oxides in the second undoped metal oxide particles independently include one or more of MoO3, WO3, NiO, CrO3, CuO, Cu2O, V2O5, the doping elements in the second doped metal oxide particles include one or more of Mo, W, Ni, Cr, Cu, V, the metal sulfides include one or more of CuS, MoS3, WS3, the metal selenides include one or more of MoSe3, WSe3, and the metal nitrides include p-type gallium nitride; Optionally, the material of the electronic functional layer includes one or more of first doped metal oxide particles, first undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The material of the first undoped metal oxide particles includes one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxides in the first doped metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping elements in the first doped metal oxide particles include one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The IIB-VIA group semiconductor materials include one or more of ZnS, ZnSe, and CdS. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS.

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