Core-shell structure quantum dots for electroluminescent device and preparation method thereof, and electroluminescent device

Abstract

The present application provides a core-shell structure quantum dot for electroluminescent device and its preparation method, electroluminescent device, the core-shell structure quantum dot includes a core body and a surface shell layer, the surface shell layer is ZnS 1‑x O x , wherein 0.1≤x≤0.9; the core-shell quantum dots of the present application can significantly improve the current density, brightness, and EQE of the electroluminescent device prepared therefrom.

Description

Technical Field

[0001] The present application belongs to the field of nanotechnology, and specifically relates to a core-shell structure quantum dot for an electroluminescent device, a preparation method thereof, and an electroluminescent device. Background Art

[0002] Quantum dot light-emitting diodes (QLEDs) are devices that emit light through direct electrical stimulation of quantum dots. Compared to traditional organic light-emitting devices (OLEDs), QLEDs offer superior color purity, brightness, and a wider color gamut. Quantum dots can be dispersed in organic solvents, allowing them to be manufactured into thin luminescent films using methods such as inkjet printing, spin coating, and doctor blade coating. These thin films are suitable for panels of varying sizes. Therefore, the QLED market holds significant promise.

[0003] A common QLED generally consists of an anode, hole transport layer, quantum dot electroluminescent layer, electron transport layer, and cathode structure from bottom to top. An external circuit injects electrons and holes into the device through the cathode and anode, respectively. The injected carriers pass through the electron transport layer and hole transport layer to the light-emitting layer to recombine and emit light. The electron transport layer of existing QLEDs uses zinc oxide, which has a fast electron migration speed, while the hole transport layer uses organic materials, which has a slow hole migration speed. This leads to an imbalance between the electrons and holes injected into the quantum dot electroluminescent layer, resulting in low efficiency and low brightness. Therefore, we urgently need to optimize quantum dots and change their conductivity to achieve better recombination of electrons and holes, thereby comprehensively improving the performance of QLEDs. Summary of the Invention

[0004] In order to solve the above technical problems, the present application provides a core-shell structure quantum dot, comprising a core body and a surface shell layer, wherein the surface shell layer is ZnS 1-x O x , where 0.1≤x≤0.9.

[0005] Furthermore, the ZnS 1-x O x , x is between 0.1 and 0.5.

[0006] Furthermore, the mass percentage of oxygen element in the core-shell structure quantum dots does not exceed 1%.

[0007] Furthermore, a surface ligand is connected to the surface shell, and the surface ligand comprises at least one of a thiol group, a carboxyl group, an amine group, an amide group, an organic phosphine group, and an organic ester group.

[0008] The present application also provides a method for preparing core-shell structure quantum dots for electroluminescent devices, comprising the steps of:

[0009] At a certain temperature, a gas containing oxygen is introduced into a dispersion containing initial quantum dots to react and form core-shell structure quantum dots, wherein the initial quantum dots include a core body and a ZnS shell layer coated outside the core body, and the core-shell structure quantum dots include a core body and a surface shell layer, wherein the surface shell layer is ZnS 1-x O x , where 0.1≤x≤0.9.

[0010] Furthermore, the gas is air.

[0011] Furthermore, the flow rate of the gas is 0.1 to 1 L / min, preferably 0.2 to 0.5 L / min.

[0012] Furthermore, the temperature is 20-100°C, preferably 30-60°C.

[0013] Furthermore, the dispersion further comprises a non-coordinating solvent, and the non-coordinating solvent comprises at least one of an aliphatic hydrocarbon and an aromatic hydrocarbon;

[0014] Preferably, the concentration of the initial quantum dots in the dispersion is 10 to 50 mg / mL.

[0015] The present application also provides an electroluminescent device, comprising a quantum dot light-emitting layer, wherein the quantum dot light-emitting layer comprises the core-shell structure quantum dots for electroluminescent devices as described above, or comprises the core-shell structure quantum dots obtained by the above-mentioned preparation method for electroluminescent devices.

[0016] Beneficial effects:

[0017] (1) The core-shell structure quantum dots of the present application include a core body and a surface shell layer, wherein the surface shell layer is ZnS 1-x O x , where 0.1≤x≤0.9, this structure can effectively enhance the conductivity of core-shell quantum dots, and the brightness and EQE of the electroluminescent devices prepared therefrom are greatly improved;

[0018] (2) The preparation method of the core-shell structure quantum dots of the present application uses air as an oxygen source to prepare ZnS 1-x O x The surface shell layer has a wide range of raw materials, is common and easily available, is non-toxic and harmless, has a simple process, and a green and environmentally friendly preparation method, and has good economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a surface energy spectrum analysis diagram of the core-shell structure quantum dots of Example 1 of the present application;

[0020] Figure 2This is a scanning electron microscope image of the core-shell structure quantum dots of Example 1 of the present application;

[0021] Figure 3 The voltage (V)-current density (A / m) of the electroluminescent device of Example 1 and Comparative Example 1 of the present application is 2 ) comparison chart;

[0022] Figure 4 This is a comparison chart of voltage (V)-brightness (nit) of the electroluminescent devices of Example 1 and Comparative Example 1 of the present application;

[0023] Figure 5 This is a comparison chart of voltage (V)-external quantum efficiency of the electroluminescent devices of Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0024] Below in conjunction with the application embodiment, the technical scheme in the application embodiment is described in detail.It should be noted that described embodiment is only a part of embodiment of the application, rather than all embodiments.If not defined in addition, all terms (including technical terms and scientific terms) in the specification can be defined as commonly understood by those skilled in the art.Unless clearly defined, otherwise the terms defined in the general dictionary can be interpreted not ideally or exaggeratedly.In addition, unless clearly described to the contrary, word "comprise" and such as "comprises" or "contains" variations will be understood to mean including stated elements (elements), but do not exclude any other elements (elements).

[0025] In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals refer to like elements throughout the specification.

[0026] It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, the element can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

[0027] In addition, unless otherwise mentioned, the singular includes the plural. As used herein, "one", "one (kind / person)", "the (described)" and "at least one (kind / person) in ... " do not represent the limitation of quantity, but are intended to include both the singular and the plural, unless the context clearly indicates otherwise. For example, unless the context clearly indicates otherwise, "element (element)" has the same meaning as "at least one element (element)". "At least one (kind / person)" is not interpreted as limiting "one" or "one (kind / person)". "Or" means "and / or". As used herein, the term "and / or" includes any combination and all combinations of one or more of the relevant listed items. It will also be understood that when the terms "comprising" and / or "including" or their variations are used in this specification, the existence of stated features, regions, wholes, steps, operations, elements and / or components is indicated, but the existence or addition of one or more other features, regions, wholes, steps, operations, elements, components and / or their groups is not excluded.

[0028] It will be understood that although the terms "first," "second," "third," etc. are used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section.

[0029] As described in the background art, the electrons and holes injected into the quantum dot electroluminescent layer of the currently common quantum dot electroluminescent devices are unbalanced, resulting in low quantum efficiency and low brightness of the QLED.

[0030] Based on this, the present application provides a core-shell structure quantum dot for electroluminescent devices, comprising a core body and a surface shell layer, wherein the surface shell layer is ZnS 1-x O x , where 0.1≤x≤0.9. The surface shell of the quantum dot includes three elements, oxygen, sulfur, and zinc, uniformly distributed on the outer surface. The presence of oxygen in the surface shell effectively regulates the conductivity of the quantum dot, allowing electrons migrating from the cathode to remain in the quantum dot light-emitting layer as much as possible and efficiently combine with holes, rather than penetrating the quantum dot light-emitting layer into the hole transport layer, thereby significantly improving the luminous efficiency and brightness of the electroluminescent device.

[0031] This application dopes oxygen elements onto the surface of quantum dots, changing the conductivity of quantum dots. By designing different proportions of oxygen element doping, the conductivity and energy level of quantum dots can be regulated, thereby finding excellent recombination conditions for electrons and holes in the electroluminescent layer, and achieving improvements in the brightness and external quantum efficiency of QLED devices.

[0032] In the first specific embodiment of the present application, ZnS 1-x Ox In the case of 0.1≤x≤0.5, the surface shell contains an appropriate amount of oxygen, which is conducive to the effective recombination of electrons and holes in the quantum dot light-emitting layer.

[0033] In the second specific embodiment of the present application, the mass percentage of oxygen in the core-shell structure quantum dots does not exceed 1%, and the oxygen content is within a reasonable range, making the conductivity of the core-shell structure quantum dots more suitable.

[0034] In the third specific embodiment of the present application, the surface shell is connected to a surface ligand, and the surface ligand includes at least one of a thiol group, a carboxyl group, an amine group, an amide, an organic phosphine, and an organic ester; the surface shell is connected to the surface ligand to make the core-shell structure quantum dots better dispersed in the quantum dot light-emitting layer, which is beneficial to the subsequent preparation of QLED devices. When the surface ligand is a carboxyl group, an amine group, an amide, an organic phosphine, or an organic ester, it is beneficial to make the core-shell structure quantum dots obtain better conductivity.

[0035] The present application also provides a method for preparing core-shell structure quantum dots for electroluminescent devices, comprising the steps of: at a certain temperature, introducing a gas containing oxygen into initial quantum dots to react and form core-shell structure quantum dots, wherein the initial quantum dots include a core body and a ZnS shell layer coated outside the core body, and the core-shell structure quantum dots include a core body and a surface shell layer, wherein the surface shell layer is ZnS 1-x O x , where 0.1≤x≤0.9. By partially oxidizing the ZnS shell of the initial quantum dots, the resulting core-shell quantum dots have improved conductivity, facilitating better recombination of holes and electrons in the quantum dot light-emitting layer.

[0036] It is understood that in the initial quantum dots of the present application, the ZnS shell layer may include several layers of ZnS molecular layers coated outside the core body. When the ZnS shell layer includes a layer of ZnS molecular layers, after the gas containing oxygen is passed into the initial quantum dots, the oxygen will oxidize some of the ZnS molecules in the ZnS molecular layer to form ZnO, thereby obtaining ZnS 1-x O x Surface shell; When the ZnS shell includes multiple ZnS molecular layers, after the gas containing oxygen is introduced into the initial quantum dots, the oxygen will oxidize some ZnS molecules in the outermost ZnS molecular layer away from the core to form ZnO, thereby obtaining ZnS 1-x O x Surface shell.

[0037] In a preferred embodiment, the oxygen content in the oxygen-containing gas is 15-60%, and the oxidation degree of the obtained core-shell structured quantum dots is more appropriate.

[0038] In one embodiment, the gas is air. Using air as an oxidant can reduce production costs and obtain a suitable reaction rate to quickly obtain partially oxidized ZnS. 1-x O x Surface shell.

[0039] In another embodiment, the gas flow rate is 0.1-1 mL / s, thereby adjusting the oxidation rate of the ZnS shell to obtain a suitable oxygen content of ZnS. 1-x O x For the surface shell layer, the gas flow rate is preferably 0.2 to 0.5 mL / s.

[0040] In another specific embodiment, the temperature is 20-100°C. Under low temperature conditions, the oxidation degree of the ZnS shell is better and the surface shell interface is complete, which is conducive to the composite luminescence of electrons and holes in the core-shell structure quantum dots. The temperature is preferably 30-60°C.

[0041] In yet another embodiment, the core comprises a II-VI compound, a III-V compound, a IV-VI compound, a I-III-VI compound, a I-II-IV-VI compound, a perovskite compound, carbon quantum dots, or a combination thereof. For example, the II-VI group compounds may include: CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, or combinations thereof. The II-VI group compound may further include a Group III metal. The III-V group compound may include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, InZnP, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, or a combination thereof. The III-V group compound may further include a Group II metal (e.g., InZnP). The IV-VI group compound may include: SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, or a combination thereof. Examples of the I-III-VI group compound may include CuInSe2, CuInS2, CuInGaSe, and CuInGaS, but are not limited thereto. Examples of the I-II-IV-VI group compound may include CuZnSnSe and CuZnSnS, but are not limited thereto. The core is coated with ZnS 1-x O xsurface shell to improve the conductivity of core-shell structure quantum dots.

[0042] In another embodiment, the dispersion containing the initial quantum dots further contains a non-coordinating solvent, and the non-coordinating solvent contains at least one of an aliphatic hydrocarbon and an aromatic hydrocarbon, so that the ZnS shell of the initial quantum dots dispersed in the non-coordinating solvent is more easily uniformly oxidized to form a ZnS with better surface energy. 1-x O x Surface shell.

[0043] In a preferred embodiment, the non-coordinating solvent of the present application is preferably at least one of n-hexane, n-heptane, toluene, and octadecene, which is conducive to partial surface oxidation reaction of the initial quantum dots; the concentration of the initial quantum dots in the dispersion is 10 to 100 mg / mL, and the oxygen reaction rate is controlled, preferably 20 to 50 mg / mL, so that the oxidation reaction rate of the surface shell is more appropriate.

[0044] The core-shell structure quantum dots of the present application are obtained by partially oxidizing the surface of the initial quantum dots. Partial surface oxidation makes the core-shell structure quantum dots more conductive and more conducive to the recombination of holes and electrons in the quantum dot light-emitting layer in the electroluminescent device.

[0045] The present application also provides an electroluminescent device, comprising a quantum dot light-emitting layer, wherein the quantum dot light-emitting layer comprises the core-shell structure quantum dots for the electroluminescent device, or comprises the core-shell structure quantum dots obtained by the above-mentioned preparation method for the electroluminescent device.

[0046] The core-shell structured quantum dots and electroluminescent devices according to some exemplary embodiments of the present application are described in more detail below; however, the exemplary embodiments of the present application are not limited thereto.

[0047] Example 1

[0048] The purified red light InP / ZnS quantum dots were added to n-heptane to prepare a 20 mg / mL solution. 5 mL of the solution was taken into a reaction bottle, plugged with a rubber stopper, set the temperature to 50 ° C, and air was blown into the solution through the needle using an air pump at an injection rate of 0.25 L / min. The reaction was carried out for 1 hour to obtain purified InP / ZnS. 0.56 O 0.44 The quantum dots have a mass percentage of oxygen element in the quantum dots of 0.44%. The quantum dots are prepared into a 17 mg / mL n-octane solution to prepare an electroluminescent device, and its performance is tested.

[0049] Example 2

[0050] The purified red light InP / ZnS quantum dots were added to n-heptane to prepare a 20 mg / mL solution. 5 mL of the solution was taken into a reaction bottle, plugged with a rubber stopper, and the temperature was set to 20 ° C. Air was blown into the solution through the needle using an air pump at an injection rate of 0.25 L / min. The reaction was carried out for 1 hour. The surface shell of the purified ZnS 0.68 O 0.32 The quantum dots have a mass percentage of oxygen element in the quantum dots of 0.32%. The quantum dots are prepared into a 17 mg / mL n-octane solution, and an electroluminescent device is prepared to test its performance.

[0051] Example 3

[0052] The purified red light InP / ZnS quantum dots were added to n-heptane to prepare a 20 mg / mL solution. 5 mL of the solution was taken into a reaction bottle, plugged with a rubber stopper, set the temperature to 80 ° C, and used an air pump to blow air into the solution through the needle at an injection rate of 0.25 L / min. The reaction was carried out for 1 hour. The surface shell of the purified ZnS 0.28 O 0.72 The mass percentage of oxygen in the quantum dots is 0.72%, and the surface energy spectrum analysis also confirms the oxygen doping ratio (see Appendix Figure 1 ), the quantum dots were prepared into a 17 mg / mL n-octane solution, and an electroluminescent device was prepared to test its performance.

[0053] Example 4

[0054] The purified red light InP / ZnS quantum dots were added to n-heptane to prepare a 20 mg / mL solution. 5 mL of the solution was added to a reaction bottle, which was plugged with a rubber stopper. The temperature was set to 80°C, and air was pumped into the solution through a needle using an air pump at an injection rate of 0.1 L / min. The reaction lasted for 1 hour, and the surface shell of the purified ZnS was obtained. 0.75 O 0.25 The quantum dots have a mass percentage of oxygen element in the quantum dots of 0.25%. The quantum dots are prepared into a 17 mg / mL n-octane solution to prepare an electroluminescent device, and its performance is tested.

[0055] Example 5

[0056] The purified red light InP / ZnS quantum dots were added to n-heptane to prepare a 20 mg / mL solution. 5 mL of the solution was added to a reaction bottle, which was plugged with a rubber stopper. The temperature was set to 80°C, and air was pumped into the solution through a needle using an air pump at an injection rate of 1 L / min. The reaction lasted for 1 hour, and the surface shell of the purified ZnS was obtained. 0.22 O 0.78The quantum dots have a mass percentage of oxygen element in the quantum dots of 0.78%. The quantum dots are prepared into a 17 mg / mL n-octane solution, and an electroluminescent device is prepared to test its performance.

[0057] Example 6

[0058] The purified red light InP / ZnS quantum dots were added to n-heptane to prepare a 50 mg / mL solution. 5 mL of the solution was added to a reaction bottle, which was plugged with a rubber stopper. The temperature was set to 80°C, and air was pumped into the solution through a needle using an air pump at an injection rate of 1 L / min. The reaction lasted for 1 hour, and the surface shell of the purified ZnS 0.84 O 0.16 The quantum dots have a mass percentage of oxygen element in the quantum dots of 0.16%. The quantum dots are prepared into a 17 mg / mL n-octane solution to prepare an electroluminescent device, and its performance is tested.

[0059] Example 7

[0060] The purified green light InP / ZnS quantum dots were added to n-heptane to prepare a 20 mg / mL solution. 5 mL of the solution was taken into a reaction bottle, plugged with a rubber stopper, set the temperature to 50 ° C, and air was blown into the solution through the needle using an air pump at an injection rate of 0.25 L / min. The reaction was carried out for 1 hour to obtain purified InP / ZnS. 0.56 O 0.44 The quantum dots have a mass percentage of oxygen element in the quantum dots of 0.23%. The quantum dots are prepared into a 15 mg / mL n-octane solution to prepare an electroluminescent device, and its performance is tested.

[0061] Example 8

[0062] The purified blue ZnSe / ZnS quantum dots were added to n-heptane to prepare a 20 mg / mL solution. 5 mL of the solution was taken into a reaction bottle, plugged with a rubber stopper, set the temperature to 30 ° C, and air was blown into the solution through the needle using an air pump at an injection rate of 1 L / min. The reaction was carried out for 1 hour to obtain a surface shell of ZnS. 0.52 O 0.48 The quantum dots have a mass percentage of oxygen element in the quantum dots of 0.64%. The quantum dots are prepared into a 13 mg / mL n-octane solution, and an electroluminescent device is prepared to test its performance.

[0063] Example 9

[0064] The purified red light CdSe / ZnS quantum dots were added to n-heptane to prepare a 20 mg / mL solution. 5 mL of the solution was taken into a reaction bottle, plugged with a rubber stopper, set the temperature to 30 ° C, and air was blown into the solution through the needle using an air pump at an injection rate of 1 L / min. The reaction was carried out for 1 hour. The surface shell of the purified ZnS 0.64 O 0.36 The quantum dots have a mass percentage of oxygen element in the quantum dots of 0.5%. The quantum dots are prepared into a 15 mg / mL n-octane solution to prepare an electroluminescent device, and its performance is tested.

[0065] Comparative Example 1

[0066] The purified red light-emitting InP / ZnS quantum dots were prepared into a 17 mg / mL n-octane solution, and an electroluminescent device was prepared to test its performance.

[0067] Comparative Example 2

[0068] The purified blue-light ZnSe / ZnS quantum dots were prepared into a 13 mg / mL n-octane solution, and an electroluminescent device was prepared to test its performance.

[0069] Comparative Example 3

[0070] The purified red light-emitting CdSe / ZnS quantum dots were prepared into a 15 mg / mL n-octane solution to prepare an electroluminescent device. The current density, brightness and maximum external quantum efficiency (EQE) at 3 V were tested. The specific results are shown in Table 1. The surface energy spectrum analysis diagram of the core-shell structure quantum dots of Example 1 is shown in FIG. Figure 1 From this, we can see that the surface shell of the core-shell quantum dots is ZnS 0.56 O 0.44 The scanning electron microscope image of the core-shell quantum dots of Example 1 is as follows: Figure 2 , from which it can be seen that the particle size of the core-shell structure quantum dots is about 8nm; the comparative relationship between the voltage-current density, voltage-brightness, and voltage-external quantum efficiency of Example 1 and Comparative Example 1 is shown as follows Figures 3-5 The performance parameters of the electroluminescent devices containing quantum dots with InP cores in Examples 1 to 7 and Comparative Example 1 are shown in Table 1, the performance parameters of the electroluminescent devices containing quantum dots with ZnSe cores in Example 8 and Comparative Example 2 are shown in Table 2, and the performance parameters of the electroluminescent devices containing quantum dots with CdSe cores in Example 9 and Comparative Example 3 are shown in Table 3.

[0071] Table 1 Performance parameters of electroluminescent devices containing quantum dots containing InP cores in Examples 1 to 7 and Comparative Example 1

[0072] serial number <![CDATA[3V current density (A / m 2 )]]> 3V brightness (nits) Maximum EQE(%) Example 1 73 1031 12.91 Example 2 68 835 12.81 Example 3 124 1548 11.95 Example 4 64 839 13.39 Example 5 135 1987 13.24 Example 6 62 995 15.03 Example 7 34 685 10.58 Comparative Example 1 58 556 9.64

[0073] Table 2 Performance parameters of electroluminescent devices containing ZnSe core quantum dots in Example 8 and Comparative Example 2

[0074] serial number <![CDATA[3V current density (A / m 2 )]]> 3V brightness (nits) Maximum EQE(%) Example 8 24 191 13.42 Comparative Example 2 6 4 6.44

[0075] Table 3 Performance parameters of the electroluminescent devices containing quantum dots containing CdSe cores in Example 9 and Comparative Example 3

[0076] serial number <![CDATA[3V current density (A / m 2 )]]> 3V brightness (nits) Maximum EQE(%) Example 9 886 14550 15.08 Comparative Example 3 246 5890 11.25

[0077] From Tables 1 to 3 above and Figures 1 to 5 It can be seen that compared with Comparative Examples 1 to 3, when the core-shell structured quantum dots of Examples 1 to 9 of the present application are used to prepare the light-emitting layer of the electroluminescent device, the obtained electroluminescent device has excellent electrical performance, and the current efficiency, brightness and EQE are significantly improved.

[0078] Although the inventors have elaborated and enumerated the technical solutions of the present application in detail, it should be understood that it is obvious for those skilled in the art to modify and / or adapt the above embodiments or adopt equivalent alternatives, which cannot deviate from the essence of the spirit of the present application. The terms appearing in the present application are used to explain and understand the technical solutions of the present application and cannot constitute a limitation on the present application.

Claims

1. A method for preparing core-shell structure quantum dots for electroluminescent devices, characterized in that: Including steps: At a temperature of 20-100°C, a gas containing oxygen is introduced into a dispersion containing initial quantum dots to react and form core-shell structure quantum dots, wherein the initial quantum dots include a core body and a ZnS shell layer coated outside the core body, and the core-shell structure quantum dots include the core body and a surface shell layer, wherein the surface shell layer is ZnS 1-x O x , wherein 0.1≤x≤0.9; the gas is air; the dispersion further comprises a non-coordinating solvent, and the non-coordinating solvent comprises at least one of aliphatic hydrocarbons and aromatic hydrocarbons.

2. The method for preparing core-shell structured quantum dots for electroluminescent devices according to claim 1, wherein: The flow rate of the gas is 0.1~1 L / min.

3. The method for preparing core-shell structured quantum dots for electroluminescent devices according to claim 1, wherein: In the dispersion, the initial quantum dot concentration is 10-100 mg / mL.

4. The method for preparing core-shell structure quantum dots for electroluminescent devices according to claim 1, characterized in that: The ZnS 1-x O x In the equation ( ), 0.1≤x≤0.

5.

5. The method for preparing core-shell structured quantum dots for electroluminescent devices according to claim 1, wherein: The mass percentage of oxygen element in the core-shell structure quantum dots does not exceed 1%.

6. The method for preparing core-shell structure quantum dots for electroluminescent devices according to claim 1, characterized in that: The surface shell is connected to a surface ligand, and the surface ligand comprises at least one of a thiol group, a carboxyl group, an amine group, an amide group, an organic phosphine group, and an organic ester group.

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