Quantum dot, preparation method thereof and light-emitting device

Abstract

The invention provides a quantum dot, a preparation method thereof and a light-emitting device. The preparation method of the quantum dot comprises the following steps: mixing a metal element M1 precursor, a carboxylic acid compound, a solvent and an amine compound to obtain a first reaction system; and mixing the non-metallic element precursor with the first reaction system to obtain the quantum dots. According to the preparation method of the quantum dot, the size of the prepared quantum dot can be adjusted by adjusting the proportional relation of the carboxylic acid compound and the amine compound and the like.

Description

Technical Field

[0001] This application relates to the field of quantum dots, and particularly to a quantum dot, a preparation method thereof, and a light-emitting device. Background Art

[0002] Quantum dots, also known as semiconductor nanocrystals, are mainly composed of II-VI group elements or III-V group elements. Since its physical size is smaller than the Bohr radius of excitons, a quantum confinement effect is caused, making quantum dots have unique optical and electrical properties, such as size quantum effect and dielectric confinement effect, and thus deriving the unique luminescent properties of quantum dots. Quantum dots (QDs) have become the most promising luminescent materials for next-generation flat panel displays and solid-state lighting applications due to their high fluorescence quantum yield, good monochromaticity, continuously tunable emission spectrum with size, strong photochemical stability and thermal stability, and the ability to be prepared by solution methods.

[0003] However, in the existing preparation process of quantum dots, there is a problem that the size of quantum dots is not easy to control, resulting in a relatively high production cost of quantum dots. Summary of the Invention

[0004] Based on this, the embodiments of this application provide a quantum dot, a preparation method thereof, and a light-emitting device.

[0005] In a first aspect, the embodiments of this application provide a preparation method of a quantum dot, including:

[0006] Mixing a metal element M1 precursor, a carboxylic acid compound, a solvent, and an amine compound to obtain a first reaction system;

[0007] Mixing a non-metal element precursor with the first reaction system and reacting to obtain a quantum dot.

[0008] In some embodiments, the mixing of the metal element M1 precursor, the carboxylic acid compound, the solvent, and the amine compound includes:

[0009] Mixing the metal element M1 precursor, the carboxylic acid compound, and the solvent at a temperature of 120°C to 140°C to obtain a mixed system;

[0010] Mixing the amine compound with the mixed system at a temperature of 150°C to 180°C to obtain the first reaction system.

[0011] In some embodiments, the carboxylic acid compound includes an aliphatic carboxylic acid with C8-C24;

[0012] Optionally, the aliphatic carboxylic acid with C8-C24 includes at least one of oleic acid, linoleic acid, stearic acid, palmitic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and arachidonic acid; and / or

[0013] The amine compound includes aliphatic amines having 8 to 36 carbon atoms;

[0014] Optionally, the aliphatic carboxylic acid having 8 to 24 carbon atoms includes at least one of oleylamine, octylamine, dioctylamine, trioctylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine; and / or

[0015] The metal element M1 in the metal element M1 precursor includes zinc element;

[0016] Optionally, the metal element M1 precursor includes at least one of zinc acetate, zinc acetylacetonate, zinc iodide, zinc bromide, zinc chloride, zinc fluoride, zinc carbonate, zinc cyanide, zinc nitrate, zinc oxide, zinc peroxide, zinc perchlorate, zinc sulfate, zinc oleate, zinc stearate, zinc laurate, zinc myristate, zinc palmitate, dimethylzinc, diethylzinc; and / or

[0017] The non-metal element in the non-metal element precursor includes at least one of selenium element, sulfur element, tellurium element;

[0018] Optionally, the non-metal element precursor includes at least one of Se-TOP, Se-TBP, Se-TPP, Se-ODE, Se-OA, Se-ODA, Se-TOA, Se-ODPA, Se-OLA, Se-OCA, Se-DPP, S-TOP, S-TBP, S-TPP, S-ODE, S-OA, S-ODA, S-TOA, S-ODPA, S-OLA, S-OCA, alkyl mercaptan, octyl mercaptan, decyl mercaptan, dodecyl mercaptan, hexadecyl mercaptan, mercaptopropylsilane, Te-TOP, Te-TBP, Te-TPP, Te-ODE, Te-OA, Te-ODA, Te-TOA, Te-ODPA, Te-OLA, Te-OCA, Te-DPP, Se-TOP-DPP; and / or

[0019] The solvent includes at least one of aliphatic hydrocarbons having 10 to 24 carbon atoms and aromatic hydrocarbons having 10 to 24 carbon atoms;

[0020] Optionally, the solvent includes at least one of octadecene and paraffin oil.

[0021] In some embodiments, the molar ratio of the carboxylic acid compound to the amine compound is 1:(0.1 - 1); and / or

[0022] The molar ratio of the metal element M1 precursor to the carboxylic acid compound is 1:(2 - 4); and / or

[0023] The molar ratio of the metal element M1 precursor to the non-metal element precursor is 1:(1.06 to 1.18); and / or

[0024] The step of mixing the non-metal element precursor with the first reaction system to obtain quantum dots includes: mixing the non-metal element precursor with the first reaction system at a temperature of 320°C to 330°C, and standing for 5 seconds to 60 seconds after mixing to obtain quantum dots.

[0025] In some embodiments, the step of mixing the non-metal element precursor with the first reaction system to obtain quantum dots further includes the following steps:

[0026] Mixing the non-metal element precursor with the first reaction system to obtain a second reaction system containing quantum dot clusters;

[0027] Mixing the metal element M2 precursor with the second reaction system to obtain quantum dots.

[0028] In some embodiments, the metal element M2 in the metal element M2 precursor includes cadmium;

[0029] Preferably, the metal element M2 precursor includes at least one of cadmium oleate, cadmium stearate, cadmium laurate, cadmium myristate, cadmium palmitate, dimethyl cadmium, diethyl cadmium, cadmium acetate, cadmium acetylacetonate, cadmium iodide, cadmium bromide, cadmium chloride, cadmium fluoride, cadmium carbonate, cadmium nitrate, cadmium oxide, cadmium perchlorate, cadmium phosphate, cadmium sulfate; and / or

[0030] The molar ratio of the metal element M1 precursor to the metal element M2 precursor is 1:(0.06 to 0.18); and / or

[0031] The step of mixing the non-metal element precursor with the first reaction system to obtain a second reaction system containing quantum dot clusters includes: mixing the non-metal element precursor with the first reaction system at a temperature of 320°C to 330°C, and standing for 5 seconds to 60 seconds after mixing to obtain a second reaction system containing quantum dot clusters; and / or

[0032] The step of mixing the metal element M2 precursor with the second reaction system to obtain quantum dots includes: mixing the metal element M2 precursor with the quantum dot clusters at a temperature of 320°C to 330°C, and standing for 60 minutes to 180 minutes after mixing to obtain quantum dots.

[0033] In some embodiments, the step of mixing the metal element M2 precursor with the second reaction system to obtain quantum dots further includes the following steps:

[0034] Mix the precursor of metal element M2 with the second reaction system to obtain an alloy quantum dot core;

[0035] Form a shell layer on the surface of the alloy quantum dot core to obtain quantum dots.

[0036] In some embodiments, the mixing of the precursor of metal element M2 with the second reaction system to obtain an alloy quantum dot core includes:

[0037] Under the temperature condition of 320 °C to 330 °C, mix the precursor of metal element M2 with the quantum dot clusters, and let it stand for 60 minutes to 180 minutes after mixing to obtain an alloy quantum dot core.

[0038] In a second aspect, an embodiment of the present application provides a quantum dot prepared by using the preparation method of the quantum dot as described above.

[0039] In a third aspect, an embodiment of the present application provides a light-emitting device, including a first electrode and a second electrode disposed opposite to each other and a quantum dot light-emitting layer disposed between the first electrode and the second electrode, and the material of the quantum dot light-emitting layer is the quantum dot as described above.

[0040] The preparation method of the quantum dot provided by the present application can adjust the reaction activity of the precursor of metal element M1 by mixing the precursor of metal element M1, a carboxylic acid compound and an amine compound, and further adjust the size of the prepared quantum dot by adjusting the proportional relationship between the carboxylic acid compound and the amine compound, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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.

[0042] Figure 1 It is the first flow chart of the preparation method of the quantum dot provided by the embodiment of the present application.

[0043] Figure 2 It is the first structural schematic diagram of the light-emitting device provided by the embodiment of the present application.

[0044] Figure 3 It is the second structural schematic diagram of the light-emitting device provided by the embodiment of the present application.

[0045] Figure 4 It is the transmission electron microscope photograph of the quantum dot prepared in Embodiment 1 of the present application.

[0046] Figure 5 It is the transmission electron microscope photograph of the quantum dot prepared in Embodiment 4 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0048] In the present application, "and / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, or B exists alone. Wherein A and B may be singular or plural.

[0049] In the present application, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one (item) below" or similar expressions refer to any combination of these items, including any combination of single item (item) or plural items (items). For example, "at least one (item) of a, b or c", or "at least one (item) of a, b and c" can both represent: a, b, c, a + b, a + c, b + c, or a + b + c, where a, b, and c can be single or multiple respectively.

[0050] In the present application, forming another layer "on" a certain layer, the so-called "on" is a broad concept, which may mean that the formed another layer is adjacent to a certain layer, or there are other spacer structure layers between the another layer and a certain layer. For example, forming a second electrode "on" the first carrier functional layer, the so-called "on" may mean that the formed second electrode is adjacent to the first carrier functional layer, or there are other spacer structure layers between the second electrode and the first carrier functional layer, such as a light-emitting layer.

[0051] The various embodiments of the present application may 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 the present application; therefore, it should be considered that the description of the range has specifically disclosed all possible sub-ranges and single values within that range. For example, it should be considered that the description of the range 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 that range, such as 1, 2, 3, 4, 5, and 6. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0052] Please refer to Figure 1 , the embodiments of the present application provide a method for preparing quantum dots, including:

[0053] S110. Mix a metal element M1 precursor, a carboxylic acid compound, a solvent, and an amine compound to obtain a first reaction system.

[0054] Exemplarily, the mixing of the metal element M1 precursor, the carboxylic acid compound, the solvent, and the amine compound includes:

[0055] Under a temperature condition of 120°C to 140°C (such as 120°C, 130°C, 140°C, etc.), mix the metal element M1 precursor, the carboxylic acid compound, and the solvent to obtain a mixed system;

[0056] Under a temperature condition of 150°C to 180°C (such as 150°C, 160°C, 170°C, 180°C, etc.), mix the amine compound with the mixed system to obtain a first reaction system.

[0057] It should be noted that since the complexation bond between the amine compound and the metal element is weak, therefore, in order to increase the complexation rate between the amine compound and the metal element, so that the amine compound can replace a part of the carboxylic acid compound to complex with the metal element, in the embodiment of the present application, the temperature of the reaction system is raised to 150°C to 180°C during the addition of the amine compound to promote the amine compound to replace the carboxylic acid compound to complex with the metal element.

[0058] Exemplarily, the carboxylic acid compound includes aliphatic carboxylic acids with C8 - C24.

[0059] Optionally, the aliphatic carboxylic acids with C8 - C24 include at least one of oleic acid, linoleic acid, stearic acid, palmitic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and arachidonic acid.

[0060] Exemplarily, the amine compound includes aliphatic amines with C8 - C36.

[0061] Optionally, the aliphatic carboxylic acids with C8 - C24 include at least one of oleylamine, octylamine, dioctylamine, trioctylamine, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine.

[0062] Exemplarily, the metal element M1 in the metal element M1 precursor includes zinc element.

[0063] Optionally, the metal element M1 precursor includes at least one of zinc acetate, zinc acetylacetonate, zinc iodide, zinc bromide, zinc chloride, zinc fluoride, zinc carbonate, zinc cyanide, zinc nitrate, zinc oxide, zinc peroxide, zinc perchlorate, zinc sulfate, zinc oleate, zinc stearate, zinc dodecanoate, zinc tetradecanoate, zinc hexadecanoate, dimethylzinc, and diethylzinc.

[0064] Exemplarily, the non-metal element in the non-metal element precursor includes at least one of selenium, sulfur, and tellurium elements.

[0065] In some embodiments, the non-metal element precursor includes at least one of Se-TOP (selenium-Tri-n-octylphosphine), Se-TBP (selenium-Tributyl phosphine), Se-TPP (selenium-triphenylphosphine), Se-ODE (selenium-1-octadecene), Se-OA (selenium-oleic acid), Se-ODA (selenium-octadecylamine), Se-TOA (selenium-trioctylamine), Se-ODPA (selenium-octadecylphosphonic acid), Se-OLA (selenium-oleylamine), Se-OCA (selenium-octylamine), Se-DPP (selenium-diphenylphosphine), S-TOP (Sulfur-Tri-n-octylphosphine), S-TBP (Sulfur-Tributyl phosphine), S-TPP (Sulfur-triphenylphosphine), S-ODE (Sulfur-1-octadecene), S-OA (Sulfur-oleic acid), S-ODA (Sulfur-octadecylamine), S-TOA (Sulfur-trioctylamine), S-ODPA (Sulfur-octadecylphosphonic acid), S-OLA (Sulfur-oleylamine), S-OCA (Sulfur-octylamine), S(triphenylphosphine), alkyl mercaptans (such as hexanethiol, octanethiol, decanethiol, dodecanethiol, and hexadecanethiol), mercaptopropylsilane, Te-TOP, Te-TBP, Te-TPP, Te-ODE, Te-OA, Te-ODA, Te-TOA, Te-ODPA, Te-OLA, Te-OCA, Te-DPP, Se-TOP-DPP.

[0066] Exemplarily, the solvent includes at least one of C10-C24 aliphatic hydrocarbons and C10-C24 aromatic hydrocarbons.

[0067] In some embodiments, the solvent includes at least one of octadecene and paraffin oil.

[0068] Exemplarily, the molar ratio of the carboxylic acid compound to the amine compound is 1:(0.1-1), such as 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, etc.

[0069] Exemplarily, the molar ratio of the metal element M1 precursor to the carboxylic acid compound is 1:(2-4), such as 1:2, 1:2.5, 1:3, 1:3.5, 1:4, etc.

[0070] Exemplarily, the molar ratio of the metal element M1 precursor to the non-metal element precursor is 1:(1.06-1.18), such as 1:1.06, 1:1.08, 1:1.10, 1:1.12, 1:1.14, 1:1.16, 1:1.18, etc.

[0071] S120, Mix the non-metal element precursor with the first reaction system and react to obtain quantum dots.

[0072] Exemplarily, the mixing of the non-metal element precursor with the first reaction system to obtain quantum dots includes:

[0073] Under the temperature condition of 320°C to 330°C (such as 320°C, 325°C, 330°C, etc.), mix the non-metal element precursor with the first reaction system, and after mixing, let it stand for 60 minutes to 180 minutes (such as 60 minutes, 80 minutes, 100 minutes, 120 minutes, 140 minutes, 160 minutes, 180 minutes, etc.) to obtain quantum dots. It can be understood that the quantum dots obtained at this time are quantum dots without a core-shell structure.

[0074] It can be understood that within the 60 minutes to 180 minutes after the non-metal element precursor is mixed with the first reaction system, the reaction between the metal element M1 precursor and the non-metal element precursor continues, so that the size of the quantum dots continuously expands.

[0075] The above method for preparing quantum dots involves blending a metal element M1 precursor, a carboxylic acid compound, and an amine compound. By adjusting the ratio between the carboxylic acid compound and the amine compound, the reactivity of the metal element M1 precursor can be adjusted, thereby regulating the size of the prepared quantum dots. It is known that the complexation bond between the amine compound and the metal element is weak, while the complexation bond between the carboxylic acid compound and the metal element is strong. The weak complexation bond is easily broken, allowing the metal element to participate in subsequent reactions, thus keeping the metal element M1 precursor highly reactive. The strong complexation bond is difficult to break, keeping the metal element M1 precursor less reactive. That is to say, when the ratio between the carboxylic acid compound and the amine compound is large, it means that the content of the carboxylic acid compound is high and the content of the amine compound is low. At this time, there are more strong complexation bonds formed between the metal element M1 precursor and the carboxylic acid compound, and fewer weak complexation bonds formed between the metal element M1 precursor and the amine compound. The reactivity of the metal element M1 precursor is relatively low, reducing the reaction rate between the metal element M1 precursor and the non-metal element precursor, and thus resulting in quantum dots with a smaller size. When the ratio between the carboxylic acid compound and the amine compound is small, it means that the content of the carboxylic acid compound is low and the content of the amine compound is high. At this time, there are fewer strong complexation bonds formed between the metal element M1 precursor and the carboxylic acid compound, and more weak complexation bonds formed between the metal element M1 precursor and the amine compound. The reactivity of the metal element M1 precursor is relatively high, increasing the reaction rate between the metal element M1 precursor and the non-metal element precursor, and thus resulting in quantum dots with a larger size.

[0076] Exemplarily, in the step of mixing the non-metal element precursor with the first reaction system to obtain quantum dots, the following steps are further included:

[0077] Mix the non-metal element precursor with the first reaction system to obtain a second reaction system containing quantum dot clusters;

[0078] Mix the metal element M2 precursor and the second reaction system to obtain quantum dots.

[0079] Exemplarily, the metal element M2 in the metal element M2 precursor includes cadmium.

[0080] Preferably, the metal element M2 precursor includes at least one of cadmium oleate, cadmium stearate, cadmium laurate, cadmium myristate, cadmium palmitate, dimethyl cadmium, diethyl cadmium, cadmium acetate, cadmium acetylacetonate, cadmium iodide, cadmium bromide, cadmium chloride, cadmium fluoride, cadmium carbonate, cadmium nitrate, cadmium oxide, cadmium perchlorate, cadmium phosphate, and cadmium sulfate.

[0081] Exemplarily, the molar ratio of the metal element M1 precursor to the metal element M2 precursor is 1:(0.06 - 0.18).

[0082] Exemplarily, the step of mixing the non-metal element precursor with the first reaction system to obtain a second reaction system containing quantum dot clusters includes:

[0083] Under a temperature condition of 320°C to 330°C (such as 320°C, 325°C, 330°C, etc.), the non-metal element precursor is mixed with the first reaction system, and after mixing, it is left standing for 5 seconds to 60 seconds (such as 5 seconds, 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, etc.) to obtain a second reaction system containing quantum dot clusters.

[0084] Exemplarily, the step of mixing the metal element M2 precursor with the second reaction system to obtain quantum dots includes: Under a temperature condition of 320°C to 330°C (such as 320°C, 325°C, 330°C, etc.), the metal element M2 precursor is mixed with the quantum dot clusters, and after mixing, it is left standing for 60 minutes to 180 minutes (such as 60 minutes, 80 minutes, 100 minutes, 120 minutes, 140 minutes, 160 minutes, 180 minutes, etc.) to obtain quantum dots. It can be understood that the quantum dots prepared at this time are alloy quantum dots without a core-shell structure.

[0085] It can be understood that after mixing the metal element M2 precursor with the second reaction system, a part of the metal element M1 in the quantum dot clusters will be replaced by the metal element M2, thereby obtaining quantum dots containing both the metal element M1 and the metal element M2. When the metal element M1 is zinc (Zn) and the metal element M2 is cadmium (Cd), since the atomic radius of cadmium is larger than that of zinc, when cadmium replaces zinc, the size of the quantum dot clusters will increase, and further the size of the obtained quantum dots will increase.

[0086] It should be noted that within the 60 minutes to 180 minutes of standing after mixing the metal element M2 precursor with the quantum dot clusters, along with the process of the metal element M1 in the quantum dot clusters being replaced by the metal element M2, since there are still a large number of metal element M1 precursors and non-metal element precursors in the second reaction system, the reaction between the metal element M1 precursor and the non-metal element precursor also continues, thereby continuously expanding the quantum dot clusters themselves, and further increasing the size of the quantum dots gradually.

[0087] The preparation method of the above alloy quantum dots involves blending a metal element M1 precursor, a carboxylic acid compound, and an amine compound. By adjusting the ratio between the carboxylic acid compound and the amine compound, the reactivity of the metal element M1 precursor can be adjusted, thereby regulating the size of the prepared quantum dots. It is known that the complexation bond between the amine compound and the metal element is weak, while the complexation bond between the carboxylic acid compound and the metal element is strong. The weak complexation bond is easily broken, enabling the metal element to participate in subsequent reactions, thus keeping the metal element M1 precursor with a relatively high reactivity. The strong complexation bond is difficult to break, resulting in the metal element M1 precursor having a relatively low reactivity. That is to say, when the ratio between the carboxylic acid compound and the amine compound is large, it means that the content of the carboxylic acid compound is high and the content of the amine compound is low. At this time, there are more strong complexation bonds formed between the metal element M1 precursor and the carboxylic acid compound, and fewer weak complexation bonds formed between the metal element M1 precursor and the amine compound. The reactivity of the metal element M1 precursor is relatively low, thereby reducing the reaction rate between the metal element M1 precursor and the non-metal element precursor, and further making the prepared alloy quantum dots have a smaller size. When the ratio between the carboxylic acid compound and the amine compound is small, it means that the content of the carboxylic acid compound is low and the content of the amine compound is high. At this time, there are fewer strong complexation bonds formed between the metal element M1 precursor and the carboxylic acid compound, and more weak complexation bonds formed between the metal element M1 precursor and the amine compound. The reactivity of the metal element M1 precursor is relatively high, thereby increasing the reaction rate between the metal element M1 precursor and the non-metal element precursor, and further making the prepared alloy quantum dots have a larger size.

[0088] Exemplarily, in the step of obtaining the quantum dots by mixing the metal element M2 precursor and the second reaction system, the following steps are further included:

[0089] Mix the metal element M2 precursor and the second reaction system to obtain an alloy quantum dot core;

[0090] Form a shell layer on the surface of the alloy quantum dot core to obtain the quantum dots. It can be understood that the quantum dots prepared at this time are alloy quantum dots with a core-shell structure.

[0091] Exemplarily, the molar ratio of the metal element M1 precursor to the metal element M2 precursor is 1:(0.06 - 0.18), such as 1:0.06, 1:0.08, 1:0.10, 1:0.12, 1:0.14, 1:0.16, 1:0.18, etc.

[0092] Exemplarily, the metal element M2 in the metal element M2 precursor includes cadmium.

[0093] In some embodiments, the metal element M2 precursor includes at least one of cadmium oleate, cadmium stearate, cadmium laurate, cadmium myristate, cadmium palmitate, dimethyl cadmium, diethyl cadmium, cadmium acetate, cadmium acetylacetonate, cadmium iodide, cadmium bromide, cadmium chloride, cadmium fluoride, cadmium carbonate, cadmium nitrate, cadmium oxide, cadmium perchlorate, cadmium phosphate, and cadmium sulfate.

[0094] Exemplarily, the obtaining of the alloy quantum dot core by mixing the metal element M2 precursor and the second reaction system includes:

[0095] Under a temperature condition of 320 °C to 330 °C (such as 320 °C, 325 °C, 330 °C, etc.), the metal element M2 precursor is mixed with the quantum dot clusters, and after mixing, it is left standing for 60 minutes to 180 minutes (such as 60 minutes, 80 minutes, 100 minutes, 120 minutes, 140 minutes, 160 minutes, 180 minutes, etc.) to obtain the alloy quantum dot core.

[0096] It can be understood that after mixing the metal element M2 precursor and the second reaction system, a part of the metal element M1 in the quantum dot clusters will be replaced by the metal element M2, thereby obtaining an alloy quantum dot core containing both the metal element M1 and the metal element M2. When the metal element M1 is zinc (Zn) and the metal element M2 is cadmium (Cd), since the atomic radius of cadmium is larger than that of zinc, when cadmium replaces zinc, the size of the quantum dot clusters will increase, and thus the size of the obtained alloy quantum dot core will increase.

[0097] It should be noted that within the 60 minutes to 180 minutes of standing after mixing the metal element M2 precursor and the quantum dot clusters, along with the process of the metal element M1 in the quantum dot clusters being replaced by the metal element M2, since there are still a large number of metal element M1 precursors and non-metal element precursors in the second reaction system, the reaction between the metal element M1 precursor and the non-metal element precursor also continues, thereby continuously expanding the quantum dot clusters themselves, and further increasing the size of the alloy quantum dot core.

[0098] Exemplarily, the forming of the shell layer on the alloy quantum dot core includes:

[0099] Under a temperature condition of 270 °C to 290 °C (such as 270 °C, 280 °C, 290 °C, etc.), the mixed system containing the alloy quantum dot core, the metal element precursor, and the non-metal element precursor is reacted for 10 minutes to 40 minutes (such as 10 minutes, 20 minutes, 30 minutes, 40 minutes, etc.) to form a shell layer on the alloy quantum dot core, and the material of the shell layer is different from that of the alloy quantum dot core.

[0100] Exemplarily, the material of the shell layer may include at least one of ZnSe, ZnCdSe, ZnCdS, CdSe, CdS, and ZnS.

[0101] For the preparation method of the alloy quantum dots with a core-shell structure described above, by blending the metal element M1 precursor, the carboxylic acid compound, and the amine compound, the reaction activity of the metal element M1 precursor can be adjusted by adjusting the proportional relationship between the carboxylic acid compound and the amine compound, and then the size of the prepared quantum dots can be regulated. It is known that the complexation bond between the amine compound and the metal element is weak, while the complexation bond between the carboxylic acid compound and the metal element is strong. The weak complexation bond is easy to break, enabling the metal element to participate in subsequent reactions, thus keeping the reaction activity of the metal element M1 precursor relatively high. The strong complexation bond is difficult to break, so the reaction activity of the metal element M1 precursor is kept relatively low. That is to say, when the ratio between the carboxylic acid compound and the amine compound is large, it means that the content of the carboxylic acid compound is high and the content of the amine compound is low. At this time, there are more strong complexation bonds formed between the metal element M1 precursor and the carboxylic acid compound, and fewer weak complexation bonds formed between the metal element M1 precursor and the amine compound. The reaction activity of the metal element M1 precursor is relatively low, which reduces the reaction rate between the metal element M1 precursor and the non-metal element precursor, and further makes the core of the prepared alloy quantum dots have a smaller size. Therefore, the finally prepared quantum dots with a core-shell structure can have a smaller size. When the ratio between the carboxylic acid compound and the amine compound is small, it means that the content of the carboxylic acid compound is low and the content of the amine compound is high. At this time, there are fewer strong complexation bonds formed between the metal element M1 precursor and the carboxylic acid compound, and more weak complexation bonds formed between the metal element M1 precursor and the amine compound. The reaction activity of the metal element M1 precursor is relatively high, which increases the reaction rate between the metal element M1 precursor and the non-metal element precursor, and further makes the core of the prepared alloy quantum dots have a larger size. Therefore, the finally prepared quantum dots with a core-shell structure can have a larger size.

[0102] Please refer to Figure 2 and Figure 3 As shown in, the embodiment of the present application further provides a light-emitting device 100, including a first electrode 10 and a second electrode 60 which are oppositely arranged, and a quantum dot light-emitting layer 40 disposed between the first electrode 10 and the second electrode 60. The quantum dot light-emitting layer 40 is the quantum dot light-emitting layer prepared by the preparation method of the quantum dot light-emitting layer in any of the above embodiments or the quantum dot light-emitting layer in any of the above embodiments.

[0103] Please refer to Figure 2, when the first electrode 10 is an anode and the second electrode 60 is a cathode, a hole injection layer 20 and a hole transport layer 30 are provided in a stacked manner between the first electrode 10 and the quantum dot light-emitting layer 40. Among them, the hole injection layer 20 is disposed close to the first electrode 10, the hole transport layer 30 is disposed close to the quantum dot light-emitting layer 40, and an electron transport layer 50 is provided between the second electrode 60 and the quantum dot thin film 41.

[0104] Please refer to Figure 3 , when the first electrode 10 is a cathode and the second electrode 60 is an anode, an electron transport layer 50 is provided between the first electrode 10 and the quantum dot light-emitting layer 40, and a hole injection layer 20 and a hole transport layer 30 are provided in a stacked manner between the second electrode 60 and the quantum dot light-emitting layer 40. Among them, the hole injection layer 20 is disposed close to the second electrode 60, and the hole transport layer 30 is disposed close to the quantum dot thin film 41.

[0105] Exemplarily, the material of the hole transport layer 30 may include at least one of 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine (α-NPD), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (Poly-TPD), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine (DNTPD), 4,4',4'-tris(N-carbazolyl)-triphenylamine (TCTA), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))] (TFB), poly(N-vinylcarbazole) (PVK) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine (NPB), poly(phenylenevinylene) (PPV), poly[2-methoxy-5-(2-ethylhexoxy)-1,4-phenylenevinylene] (MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MOMO-PPV), 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-omeTAD), 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (TAPC), 1,3-bis(carbazol-9-yl)benzene (MCP), polyaniline, polypyrrole, poly(p-phenylenevinylene), aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT:PSS) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, polysfluorene and its derivatives, polythiophene (TPH) and its derivatives.

[0106] Exemplarily, the material of the hole injection layer 20 may include at least one of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), copper phthalocyanine (CuPc), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN), poly(3,4-dioxythiophene) (PEDOT), a derivative of PEDOT:PSS doped with MoO3 (PEDOT:PSS-MoO3), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), tetracyanoquinodimethane (F4-TCNQ), transition metal oxides, and transition metal chalcogenides. Exemplarily, the transition metal oxides may include MoO x 、VO x 、WO x 、CrO x 、one or more of CuO. Exemplarily, the metal chalcogenides may include one or more of MoS2, MoSe2, WS2, WSe2, CuS.

[0107] Exemplarily, the material of the electron transport layer 50 may include at least one of metal oxides, doped metal oxides, group II-VI semiconductor materials, group III-V semiconductor materials, and group I-III-VI semiconductor materials. The metal oxides are selected from at least one of ZnO, BaO, TiO2, and SnO2; the metal oxides in the doped metal oxides are selected from at least one of ZnO, TiO2, and SnO2, and the doping elements are selected from at least one of Al, Mg, Li, In, and Ga. The group II-VI semiconductor materials are selected from at least one of ZnS, ZnSe, and CdS; the group III-V semiconductor materials are selected from at least one of InP and GaP; the group I-III-VI semiconductor materials are selected from at least one of CuInS and CuGaS.

[0108] In some embodiments, the material of the electron transport layer 50 is ZMO (magnesium-doped zinc oxide), which refers to magnesium-doped zinc oxide obtained by adding a Mg precursor (such as magnesium acetate, magnesium chloride, magnesium nitrate, etc.) during the synthesis of zinc oxide.

[0109] Exemplarily, the material of the electron transport layer 50 may be nanoparticles with various morphologies such as nanospheres, nanosheets, and nanorods. The average particle size of the material of the electron transport layer 50 is 2 nm to 15 nm, such as 2 nm, 5 nm, 10 nm, 12 nm, 15 nm, etc.

[0110] Exemplarily, the first electrode 10 and the second electrode 60 can each independently be selected from a doped metal oxide electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal elemental electrode, or an alloy electrode. The material of the doped metal oxide electrode can include, but is not limited to, one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO), aluminum-doped magnesium oxide (AMO), and cadmium-doped zinc oxide. The composite electrode is an electrode formed by laminating two or more layers of conductive materials. For example, AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, BaF2 / Ca / Al, etc. Herein, " / " represents a laminated structure. For example, AZO / Ag / AZO represents a composite electrode including an AZO layer, an Ag layer, and an AZO layer laminated in sequence. The material of the metal elemental electrode can include, but is not limited to, one or more of silver (Ag), magnesium (Mg), aluminum (Al), gold (Au), gallium (Ga), nickel (Ni), platinum (Pt), iridium (Ir), copper (Cu), molybdenum (Mo), calcium (Ca), and barium (Ba). The alloy electrode includes, but is not limited to, an Au:Mg alloy electrode or an Ag:Mg alloy electrode.

[0111] In some embodiments, the anode can be an electrode with a relatively high work function. For example, it can include, but is not limited to, one or more of a doped metal oxide electrode with a relatively high work function, a metal elemental electrode with a relatively high work function, and a carbon nanotube electrode. The material of the metal elemental electrode with a relatively high work function can be Ni, Pt, Au, Ag, Ir, etc.

[0112] In some embodiments, the cathode can be an electrode with a relatively low work function. For example, it can include, but is not limited to, a metal elemental electrode with a relatively low work function, a composite electrode with a relatively low work function, and an alloy electrode with a relatively low work function. The material of the metal elemental electrode with a relatively low work function can be Ca, Ba, Al, Mg, etc. The structure of the composite electrode with a relatively low work function can be Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, BaF2 / Ca / Al, etc. The alloy electrode with a relatively low work function can be Au:Mg or Ag:Mg, etc.

[0113] Exemplarily, the thickness of the hole transport layer 30 is 10 nm - 100 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc. In some embodiments, the thickness of the hole transport layer 30 is 70 nm - 90 nm.

[0114] Exemplarily, the thickness of the hole injection layer 20 is 20 nm - 120 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, etc. In some embodiments, the thickness of the hole injection layer 20 is 70 nm - 90 nm.

[0115] Exemplarily, the thickness of the quantum dot thin film 41 is 10 nm - 80 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, etc. In some embodiments, the thickness of the quantum dot thin film 41 is 60 nm - 80 nm.

[0116] Exemplarily, the thickness of the electron transport layer 50 is 15 nm - 60 nm, such as 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, etc. In some embodiments, the thickness of the electron transport layer 50 is 40 nm - 60 nm.

[0117] Exemplarily, the thicknesses of the first electrode 10 and the second electrode 60 are each 10 nm - 125 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 125 nm, etc. In some embodiments, the thickness of the anode is 115 nm - 125 nm, and the thickness of the cathode is 55 nm - 65 nm.

[0118] The embodiment of the present application further provides a display device, including the light-emitting device 100 prepared by the preparation method of the light-emitting device in any of the above embodiments or the light-emitting device 100 in any of the above embodiments.

[0119] Exemplarily, the display device may be a terminal such as a television, a mobile phone, a tablet computer, a display, an advertising display screen, etc., or may also be a device with a display screen such as a game device, an augmented reality (AR) device, a virtual reality (VR) device, a data storage device, an audio playback device, a video playback device, a wearable device, etc., where the wearable device may be a smart bracelet, smart glasses, a smart watch, smart decoration, etc.

[0120] The quantum dots, their preparation methods, and light-emitting devices of the present application will be described in detail in the form of specific embodiments below.

[0121] Quantum Dot Example 1

[0122] A kind of quantum dots, and its preparation method includes:

[0123] Step 1: Weigh 10 mmol of zinc acetate, 10 mL of oleic acid (31 mmol), and 10 ml of octadecene and place them in a 100 ml three-necked flask, and treat them under vacuum at 80 °C for 60 minutes. Then, heat at 140 °C for 30 minutes under an argon atmosphere.

[0124] Step 2: Add 10 mL of oleylamine (30.4 mmol) at 150 °C and react for 10 minutes, then raise the temperature to 330 °C.

[0125] Step 3: Inject 1.3 mmol of Se-TOP-DPP into the solvent in Step 2, and inject 0.13 mmol of cadmium oleate after 60 seconds, and react at 330 °C for 120 minutes to obtain an alloy quantum dot core.

[0126] Step 4: Add 3 mmol of S-TOP to the reaction system in Step 3, and then react for 20 minutes to form a shell layer on the surface of the alloy quantum dot core, obtaining quantum dots with a core-shell structure (Zn 0.9 Cd 0.1 Se / ZnS).

[0127] Step 5: Mix 10 ml of n-hexane, 10 ml of ethyl acetate, and 15 ml of ethanol as a cleaning solution, and divide it into two tubes of cleaning solution.

[0128] Step 6: Purification: Cool the quantum dot solution obtained in Step 4 to 130 °C. Divide the quantum dot solution into two tubes, add each tube of the quantum dot solution to one tube of the cleaning solution prepared in Step 5, put it into a centrifuge, centrifuge at 7300 rpm for 3 minutes. After the separation is completed, pour out the supernatant. Add 4 ml of n-hexane to the remaining solid quantum dot products in the two tubes for dispersion, and shake on a shaker to redisperse.

[0129] Use a transmission electron microscope to test the particle size of the quantum dots. The average particle size of the quantum dots prepared in Quantum Dot Example 1 is measured to be 8.9 nm, as Figure 3 shown, which is the transmission electron microscope photo of the quantum dots prepared in Quantum Dot Example 1 of the present application.

[0130] Quantum Dot Example 2

[0131] A kind of quantum dots, compared with Quantum Dot Example 1, the difference in its preparation method lies in:

[0132] In Step 2, 5 mL of oleylamine (15.2 mol) was added at 150 °C.

[0133] The particle size of the quantum dots was measured using a transmission electron microscope. The average particle size of the quantum dots prepared in Quantum Dot Example 2 was 8.2 nm.

[0134] Quantum Dot Example 3

[0135] A kind of quantum dots, compared with Quantum Dot Example 1 in its preparation method, the differences are as follows:

[0136] In Step 2, 2.6 mL of oleylamine (7.9 mol) was added at 150 °C.

[0137] The particle size of the quantum dots was measured using a transmission electron microscope. The average particle size of the quantum dots prepared in Quantum Dot Example 3 was 7.4 nm.

[0138] Quantum Dot Example 4

[0139] A kind of quantum dots, compared with Quantum Dot Example 1 in its preparation method, the differences are as follows:

[0140] In Step 2, 1.5 mL of oleylamine (4.6 mol) was added at 150 °C.

[0141] The particle size of the quantum dots was measured using a transmission electron microscope. The average particle size of the quantum dots prepared in Quantum Dot Example 4 was 6.0 nm, as Figure 4 shown, which is the transmission electron microscope photograph of the quantum dots prepared in Quantum Dot Example 4 of the present application.

[0142] It can be seen that the quantum dots prepared in Quantum Dot Example 1, Quantum Dot Example 2, Quantum Dot Example 3, and Quantum Dot Example 4 are all core-shell structure quantum dots composed of alloy quantum dot cores and shell layers. By comparing Quantum Dot Example 1, Quantum Dot Example 2, Quantum Dot Example 3, and Quantum Dot Example 4, it can be seen that the particle sizes of the quantum dots prepared in Quantum Dot Example 1, Quantum Dot Example 2, Quantum Dot Example 3, and Quantum Dot Example 4 gradually decrease. It is known that the differences between Quantum Dot Example 1, Quantum Dot Example 2, Quantum Dot Example 3, and Quantum Dot Example 4 are that during the preparation of the quantum dots, the addition amount of oleylamine (amine compound) gradually decreases, that is, the ratio of oleic acid (carboxylic acid compound) to oleylamine (amine compound) gradually increases. It is known that when the ratio of oleic acid (carboxylic acid compound) to oleylamine (amine compound) gradually increases, the reaction activity of zinc acetate (metal element M1 precursor) gradually decreases, resulting in a decrease in the reaction rate between zinc acetate (metal element M1 precursor) and the non-metal element precursor, and further leading to a decrease in the size of the obtained alloy quantum dot core, and finally reducing the size of the prepared core-shell structure quantum dots.

[0143] Quantum Dot Example 5

[0144] A quantum dot, the preparation method of which comprises:

[0145] Step 1: Weigh 10 mmol of zinc acetate, 10 mL of oleic acid (31 mmol), and 10 ml of octadecene and place them in a 100 ml three-necked flask, and treat them under vacuum at 80 °C for 60 minutes. Then, heat at 140 °C for 30 minutes under an argon atmosphere.

[0146] Step 2: Add 10 mL of oleylamine (30.4 mmol) at 150 °C and react for 10 minutes, then raise the temperature to 330 °C.

[0147] Step 3: Inject 1.3 mmol of Se-TOP-DPP into the solvent in Step 2, inject 0.13 mmol of cadmium oleate after 60 seconds, and react at 330 °C for 120 minutes to obtain a quantum dot (Zn 0.9 Cd 0.1 Se).

[0148] Step 4: Mix 10 ml of n-hexane, 10 ml of ethyl acetate, and 15 ml of ethanol as a cleaning solution, and divide it into two tubes of cleaning solution.

[0149] Step 5: Purification: Cool the quantum dot solution obtained in Step 3 to 130 °C, divide the quantum dot solution into two tubes, add each tube of the quantum dot solution to one tube of the cleaning solution prepared in Step 4, put it into a centrifugal device, centrifuge at 7300 rpm for 3 minutes, pour out the supernatant after separation is completed, add 4 ml of n-hexane to the remaining solid quantum dot products in the two tubes for dispersion, and shake on a shaker to redisperse.

[0150] Use a transmission electron microscope to test the particle size of the quantum dot, and the average particle size of the quantum dot prepared in Quantum Dot Example 5 is measured to be 7.2 nm.

[0151] Quantum Dot Example 6

[0152] A quantum dot, the difference in its preparation method compared with Quantum Dot Example 5 is that:

[0153] In Step 2, add 5 mL of oleylamine (15.2 mol) at 150 °C.

[0154] Use a transmission electron microscope to test the particle size of the quantum dot, and the average particle size of the quantum dot prepared in Quantum Dot Example 6 is measured to be 5.7 nm.

[0155] Quantum Dot Example 7

[0156] A quantum dot, the difference in its preparation method compared with Quantum Dot Example 1 is that:

[0157] In Step 2, 2.6 mL of oleylamine (7.9 mol) was added at 150 °C.

[0158] The particle size of the quantum dots was measured using a transmission electron microscope. The average particle size of the quantum dots prepared in Quantum Dot Example 7 was 4.5 nm.

[0159] It can be seen that the quantum dots prepared in Quantum Dot Example 5, Quantum Dot Example 6, and Quantum Dot Example 7 are all alloy quantum dots without a core-shell structure. By comparing Quantum Dot Example 5, Quantum Dot Example 6, and Quantum Dot Example 7, it can be seen that the particle sizes of the quantum dots prepared in Quantum Dot Example 5, Quantum Dot Example 6, and Quantum Dot Example 7 gradually decrease. It is known that the differences between Quantum Dot Example 5, Quantum Dot Example 6, and Quantum Dot Example 7 are as follows: during the preparation of the quantum dots, the addition amount of oleylamine (amine compound) gradually decreases, that is, the ratio of oleic acid (carboxylic acid compound) to oleylamine (amine compound) gradually increases. It is known that when the ratio of oleic acid (carboxylic acid compound) to oleylamine (amine compound) gradually increases, the reaction activity of zinc acetate (precursor of metal element M1) gradually decreases, resulting in a decrease in the reaction rate between zinc acetate (precursor of metal element M1) and the non-metal element precursor, and further leading to a decrease in the size of the prepared quantum dots.

[0160] Quantum Dot Example 8

[0161] A kind of quantum dots, whose preparation method includes:

[0162] Step 1: Weigh 10 mmol of zinc acetate, 10 mL of oleic acid (31 mmol), and 10 mL of octadecene and place them in a 100 mL three-necked flask. Treat them under vacuum at 80 °C for 60 minutes. Then, heat them at 140 °C for 30 minutes under an argon atmosphere.

[0163] Step 2: Add 10 mL of oleylamine (30.4 mmol) at 150 °C and react for 10 minutes, then raise the temperature to 330 °C.

[0164] Step 3: Inject 1.3 mmol of Se-TOP-DPP into the solvent in Step 2 and react at 330 °C for 120 minutes to obtain quantum dots (ZnSe).

[0165] Step 4: Mix 10 mL of n-hexane, 10 mL of ethyl acetate, and 15 mL of ethanol as the cleaning solution and divide it into two tubes of cleaning solution.

[0166] Step 5, Purification: Cool the quantum dot solution obtained in Step 3 to 130 °C. Divide the quantum dot solution into two tubes, and add each tube of the quantum dot solution to one tube of the cleaning solution prepared in Step 4. Place them in a centrifuge, centrifuge at 7300 rpm for 3 minutes. After the separation is completed, pour off the supernatant. Add 4 ml of n-hexane to the remaining solid quantum dot products in the two tubes for dispersion, and shake on a shaker to redisperse.

[0167] Use a transmission electron microscope to measure the particle size of the quantum dots. The average particle size of the quantum dots prepared in Quantum Dot Example 8 is measured to be 6.2 nm.

[0168] Quantum Dot Example 9

[0169] A quantum dot, the difference in its preparation method compared with Quantum Dot Example 8 is that:

[0170] In Step 2, add 5 mL of oleylamine (15.2 mol) at 150 °C.

[0171] Use a transmission electron microscope to measure the particle size of the quantum dots. The average particle size of the quantum dots prepared in Quantum Dot Example 9 is measured to be 4.8 nm.

[0172] Quantum Dot Example 10

[0173] A quantum dot, the difference in its preparation method compared with Quantum Dot Example 8 is that:

[0174] In Step 2, add 2.6 mL of oleylamine (7.9 mol) at 150 °C.

[0175] Use a transmission electron microscope to measure the particle size of the quantum dots. The average particle size of the quantum dots prepared in Quantum Dot Example 10 is measured to be 3.1 nm.

[0176] It can be seen that the quantum dots prepared in Quantum Dot Example 8, Quantum Dot Example 9, and Quantum Dot Example 10 are all single-metal-element quantum dots without a core-shell structure. By comparing Quantum Dot Example 8, Quantum Dot Example 9, and Quantum Dot Example 10, it can be seen that the particle sizes of the quantum dots prepared in Quantum Dot Example 8, Quantum Dot Example 9, and Quantum Dot Example 10 gradually decrease. It is known that the differences between Quantum Dot Example 8, Quantum Dot Example 9, and Quantum Dot Example 10 are as follows: during the preparation of the quantum dots, the addition amount of oleylamine (amine compound) gradually decreases, that is, the ratio of oleic acid (carboxylic acid compound) to oleylamine (amine compound) gradually increases. It is known that when the ratio of oleic acid (carboxylic acid compound) to oleylamine (amine compound) gradually increases, the reaction activity of zinc acetate (precursor of metal element M1) gradually decreases, resulting in a decrease in the reaction rate between zinc acetate (precursor of metal element M1) and the non-metal element precursor, and further leading to a decrease in the size of the prepared quantum dots.

[0177] Device Embodiment 1

[0178] A light-emitting device, comprising an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode that are sequentially stacked;

[0179] The material of the anode is ITO, the material of the hole injection layer is PEDOT:PSS, the material of the hole transport layer is TFB, the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Embodiment 1, the material of the electron transport layer is zinc oxide nanoparticles (average particle size is 3.5 nm), and the material of the cathode is silver (Ag);

[0180] The thickness of the anode is 30 nm, the thickness of the hole injection layer is 80 nm, the thickness of the hole transport layer is 40 nm, the thickness of the light-emitting layer is 70 nm, the thickness of the electron transport layer is 50 nm, and the thickness of the cathode is 60 nm.

[0181] Device Embodiment 2

[0182] A light-emitting device, different from Device Embodiment 1 in that: the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Embodiment 2.

[0183] Device Embodiment 3

[0184] A light-emitting device, different from Device Embodiment 1 in that: the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Embodiment 3.

[0185] Device Embodiment 4

[0186] A light-emitting device, different from Device Embodiment 1 in that: the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Embodiment 4.

[0187] Device Embodiment 5

[0188] A light-emitting device, different from Device Embodiment 1 in that: the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Embodiment 5.

[0189] Device Embodiment 6

[0190] A light-emitting device, different from Device Embodiment 1 in that: the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Embodiment 6.

[0191] Device Embodiment 7

[0192] A light-emitting device, different from Device Embodiment 1 in that: the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Embodiment 7.

[0193] Device Embodiment 8

[0194] A light-emitting device, which is different from Device Example 1 in that: the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Example 8.

[0195] Device Example 9

[0196] A light-emitting device, which is different from Device Example 1 in that: the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Example 9.

[0197] Device Example 10

[0198] A light-emitting device, which is different from Device Example 1 in that: the material of the light-emitting layer is the quantum dots prepared in Quantum Dot Example 10.

[0199] Device Comparative Example 1

[0200] A light-emitting device, which is different from Device Example 1 in that: the material of the light-emitting layer is commercially available Zn 0.9 Cd 0.1 Se / ZnS quantum dots with an average particle size of 7.5 nm.

[0201] Device Comparative Example 2

[0202] A light-emitting device, which is different from Device Example 1 in that: the material of the light-emitting layer is commercially available Zn 0.9 Cd 0.1 Se quantum dots with an average particle size of 5.5 nm.

[0203] Device Comparative Example 3

[0204] A light-emitting device, which is different from Device Example 1 in that: the material of the light-emitting layer is commercially available ZnSe quantum dots with an average particle size of 4.5 nm.

[0205] Performance Test:

[0206] Perform performance tests on the light-emitting devices prepared in Device Examples 1-10. The test indicators and test methods are as follows:

[0207] Luminous efficiency C.E. (cd / A): Measured using an optical test instrument (FushiDa FPD Optical Property Measurement Equipment, F-STAR Optical Measurement Systems);

[0208] Device T95_1knit life (hours): Refers to the life of the device when the brightness decays to 95% at an initial brightness of 1000 nits.

[0209] The test results are shown in Table 1.

[0210] Table 1

[0211]

[0212]

[0213] It can be seen from the data in Table 1 that:

[0214] The luminous efficiency C.E. and T95_1knit lifetime of the light-emitting devices of Device Examples 1-4 are both greater than those of the light-emitting devices of Device Comparative Example 1. It is known that the only difference between Device Examples 1-4 and Device Comparative Example 1 is that: the material of the light-emitting layer in the light-emitting devices of Device Examples 1-4 is the Zn 0.9 Cd 0.1 Se / ZnS quantum dots prepared in Quantum Dot Examples 1-4 of the present application, while the material of the light-emitting layer in the light-emitting devices of Device Comparative Example 1 is commercially available Zn 0.9 Cd 0.1 Se / ZnS quantum dots, which indicates that the quantum dots prepared in Quantum Dot Examples 1-4 of the present application have good luminous performance and stability;

[0215] The luminous efficiency C.E. and T95_1knit lifetime of the light-emitting devices of Device Examples 5-7 are both greater than those of the light-emitting devices of Device Comparative Example 2. It is known that the only difference between Device Examples 5-7 and Device Comparative Example 2 is that: the material of the light-emitting layer in the light-emitting devices of Device Examples 5-7 is the Zn 0.9 Cd 0.1 Se quantum dots prepared in Quantum Dot Examples 5-7 of the present application, while the material of the light-emitting layer in the light-emitting devices of Device Comparative Example 2 is commercially available Zn 0.9 Cd 0.1 Se quantum dots, which indicates that the quantum dots prepared in Quantum Dot Examples 5-7 of the present application have good luminous performance and stability;

[0216] The luminous efficiency C.E. and T95_1knit lifetime of the light-emitting devices of Device Examples 8-10 are both greater than those of the light-emitting devices of Device Comparative Example 3. It is known that the only difference between Device Examples 8-10 and Device Comparative Example 3 is that: the material of the light-emitting layer in the light-emitting devices of Device Examples 8-10 is the ZnSe quantum dots prepared in Quantum Dot Examples 8-10 of the present application, while the material of the light-emitting layer in the light-emitting devices of Device Comparative Example 3 is commercially available ZnSe quantum dots, which indicates that the quantum dots prepared in Quantum Dot Examples 8-10 of the present application have good luminous performance and stability.

[0217] The above has introduced in detail the quantum dots, their preparation methods, and light-emitting devices provided by the embodiments of the present application. Specific examples are used herein to elaborate on the principles and implementation manners of the present application. The descriptions of the above embodiments are only for helping to understand 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 manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A method for preparing quantum dots, characterized in that, Comprising: Mixing a metal element M1 precursor, a carboxylic acid compound, a solvent, and an amine compound to obtain a first reaction system; Mixing a non-metal element precursor with the first reaction system and reacting to obtain quantum dots.

2. The preparation method of the quantum dots according to claim 1, characterized in that, The mixing of the metal element M1 precursor, the carboxylic acid compound, the solvent, and the amine compound comprises: Under a temperature condition of 120°C to 140°C, mixing the metal element M1 precursor, the carboxylic acid compound, and the solvent to obtain a mixed system; Under a temperature condition of 150°C to 180°C, mixing the amine compound with the mixed system to obtain the first reaction system.

3. The preparation method of the quantum dots according to claim 1, wherein The carboxylic acid compound includes aliphatic carboxylic acids with C8 - C24; Optionally, the C8 - C24 aliphatic carboxylic acids include at least one of oleic acid, linoleic acid, stearic acid, palmitic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, arachidonic acid; and / or The amine compound includes aliphatic amines with C8 - C36; Optionally, the C8 - C24 aliphatic carboxylic acids include at least one of oleylamine, octylamine, dioctylamine, trioctylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine; and / or The metal element M1 in the metal element M1 precursor includes zinc element; Optionally, the metal element M1 precursor includes at least one of zinc acetate, zinc acetylacetonate, zinc iodide, zinc bromide, zinc chloride, zinc fluoride, zinc carbonate, zinc cyanide, zinc nitrate, zinc oxide, zinc peroxide, zinc perchlorate, zinc sulfate, zinc oleate, zinc stearate, zinc dodecanoate, zinc tetradecanoate, zinc hexadecanoate, dimethylzinc, diethylzinc; and / or The non-metal element in the non-metal element precursor includes at least one of selenium element, sulfur element, tellurium element; Optionally, the non-metal element precursor includes at least one of Se-TOP, Se-TBP, Se-TPP, Se-ODE, Se-OA, Se-ODA, Se-TOA, Se-ODPA, Se-OLA, Se-OCA, Se-DPP, S-TOP, S-TBP, S-TPP, S-ODE, S-OA, S-ODA, S-TOA, S-ODPA, S-OLA, S-OCA, alkyl mercaptan, octyl mercaptan, decyl mercaptan, dodecyl mercaptan, hexadecyl mercaptan, mercaptopropyl silane, Te-TOP, Te-TBP, Te-TPP, Te-ODE, Te-OA, Te-ODA, Te-TOA, Te-ODPA, Te-OLA, Te-OCA, Te-DPP, Se-TOP-DPP; and / or The solvent includes at least one of C10 - C24 aliphatic hydrocarbons, C10 - C24 aromatic hydrocarbons; Optionally, the solvent includes at least one of octadecene, paraffin oil.

4. The preparation method of the quantum dots according to claim 1, wherein, The molar ratio of the carboxylic acid compound to the amine compound is 1:(0.1 - 1); and / or The molar ratio of the metal element M1 precursor to the carboxylic acid compound is 1:(2 - 4); and / or The molar ratio of the metal element M1 precursor to the non-metal element precursor is 1:(1.06 - 1.18); and / or The method of mixing the non-metal element precursor with the first reaction system to obtain quantum dots includes: under the temperature condition of 320°C - 330°C, mixing the non-metal element precursor with the first reaction system, and standing for 5 seconds - 60 seconds after mixing to obtain quantum dots.

5. The preparation method of the quantum dots according to claim 1, characterized in that, In the method of mixing the non-metal element precursor with the first reaction system to obtain quantum dots, the following steps are further included: Mixing the non-metal element precursor with the first reaction system to obtain a second reaction system containing quantum dot clusters; Mixing the metal element M2 precursor with the second reaction system to obtain quantum dots.

6. The preparation method of the quantum dots according to claim 5, wherein The metal element M2 in the metal element M2 precursor includes cadmium; Preferably, the metal element M2 precursor includes at least one of cadmium oleate, cadmium stearate, cadmium laurate, cadmium myristate, cadmium palmitate, dimethyl cadmium, diethyl cadmium, cadmium acetate, cadmium acetylacetonate, cadmium iodide, cadmium bromide, cadmium chloride, cadmium fluoride, cadmium carbonate, cadmium nitrate, cadmium oxide, cadmium perchlorate, cadmium phosphate, cadmium sulfate; and / or The molar ratio of the metal element M1 precursor to the metal element M2 precursor is 1:(0.06 - 0.18); and / or The method of mixing the non-metal element precursor with the first reaction system to obtain a second reaction system containing quantum dot clusters includes: under the temperature condition of 320°C - 330°C, mixing the non-metal element precursor with the first reaction system, and standing for 5 seconds - 60 seconds after mixing to obtain a second reaction system containing quantum dot clusters; and / or The method of mixing the metal element M2 precursor with the second reaction system to obtain quantum dots includes: under the temperature condition of 320°C - 330°C, mixing the metal element M2 precursor with the quantum dot clusters, and standing for 60 minutes - 180 minutes after mixing to obtain quantum dots.

7. The preparation method of the quantum dots according to claim 5, characterized in that, In the method of mixing the metal element M2 precursor with the second reaction system to obtain quantum dots, the following steps are further included: Mixing the metal element M2 precursor with the second reaction system to obtain an alloy quantum dot core; Forming a shell layer on the surface of the alloy quantum dot core to obtain quantum dots.

8. The method for preparing quantum dots according to claim 7, characterized in that, The method of mixing the metal element M2 precursor with the second reaction system to obtain an alloy quantum dot core includes: Under the temperature condition of 320°C - 330°C, mixing the metal element M2 precursor with the quantum dot clusters, and standing for 60 minutes - 180 minutes after mixing to obtain an alloy quantum dot core.

9. A quantum dot, characterized in that, Prepared by the method for preparing quantum dots according to any one of claims 1 - 8.

10. A light-emitting device, characterized in that, It includes a first electrode and a second electrode arranged oppositely and a quantum dot light-emitting layer disposed between the first electrode and the second electrode, and the material of the quantum dot light-emitting layer is the quantum dot according to claim 9.

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