CN113046057A

CN113046057A - Quantum dot, core-shell quantum dot prepared from quantum dot and preparation method of core-shell quantum dot

Info

Publication number: CN113046057A
Application number: CN202110242463.9A
Authority: CN
Inventors: 单玉亮; 曹佳佳; 曹越峰; 李岩; 王允军
Original assignee: Suzhou Xingshuo Nanotech Co Ltd
Current assignee: Suzhou Xingshuo Nanotech Co Ltd
Priority date: 2021-03-05
Filing date: 2021-03-05
Publication date: 2021-06-29

Abstract

The application provides a quantum dot, a core-shell quantum dot prepared from the quantum dot and a preparation method of the quantum dot, wherein the quantum dot comprises a body and a group IIB-VIA compound or a group IIIA-VA compound; and an organic ligand derived from a compound represented by formula (1): r¹‑X‑Si(OR²)₃(1) Wherein R is¹Is mercapto for connecting the body, X comprises at least one of polar organic chain segment and nonpolar organic chain segment, R²An end group on the side of the organic ligand remote from the bulk; the core-shell quantum dot prepared by hydrolyzing the quantum dot has good stability and high quantum efficiency, and the preparation method of the core-shell quantum dotThe method has simple process, is green and environment-friendly, and has certain economic benefit and social benefit.

Description

Quantum dot, core-shell quantum dot prepared from quantum dot and preparation method of core-shell quantum dot

Technical Field

The application belongs to the field of nano materials, and particularly relates to a quantum dot, a core-shell quantum dot prepared from the quantum dot and a preparation method of the core-shell quantum dot.

Background

Quantum dots (also called semiconductor nanocrystals) are a new type of semiconductor nanomaterial with a size of 1-10 nm. They have unique Photoluminescent (PL) and Electroluminescent (EL) properties due to quantum size effects and dielectric confinement effects. Compared with the traditional organic fluorescent dye, the quantum dot has excellent optical characteristics of high quantum efficiency, high photochemical stability, difficult photolysis, wide excitation, narrow emission, high color purity, adjustable luminescent color by controlling the size of the quantum dot and the like, and has wide application prospect in the technical field of display.

At present, cadmium quantum dots have the advantages of high quantum efficiency, small half-peak width, strong blue light absorption and good stability, and have gradually begun to be commercialized, but due to the existence of heavy metal element cadmium, the cadmium-free quantum dots cannot meet the increasingly important environmental protection requirements, so the development of novel cadmium-free quantum dots is very urgent. At present, the shell layer material commonly used by the novel environment-friendly quantum dot InP is ZnSe or ZnS, and the quantum dot is easily affected by water vapor and oxygen, so that the performance of the quantum dot is rapidly reduced, the stability of the InP quantum dot in the air is poor, and the real commercial application cannot be realized. Therefore, it is urgently needed to optimize the synthesis mode of the cadmium-free quantum dots, add an outer shell layer with good stability and strong resistance to water-oxygen corrosion, and improve the performance, thereby promoting the cadmium-free quantum dots to realize commercialization more quickly.

Disclosure of Invention

To solve the above technical problem, the present application provides a quantum dot, comprising:

a body comprising a group IIB-VIA compound or a group IIIA-VA compound; and

an organic ligand derived from a compound represented by formula (1): r¹-X-Si(OR²)₃ (1)

Wherein R is¹Is mercapto for connecting the body, X comprises at least one of polar organic chain segment and nonpolar organic chain segment, R²Is the end group of the organic ligand on the side remote from the bulk.

Further, the mass percentage of the organic ligand in the quantum dot is 10-50%.

Further, R²Including at least one of hydrogen and alkyl.

The present application also provides a core-shell quantum dot, comprising:

a body comprising a group IIB-VIA compound or a group IIIA-VA compound; and

a casing layer comprising a polysiloxane;

the body is connected with an X group through a mercapto group, the X group is connected with the polysiloxane, and the X group comprises at least one of a polar organic chain segment and a non-polar organic chain segment.

The application also provides a preparation method of the core-shell quantum dot, which comprises the following steps:

s1, reacting the initial quantum dot with a compound represented by formula (1) to form the above quantum dot;

s2, reacting the quantum dot with a solution containing water, acid or alkali to form a core-shell quantum dot, wherein the core-shell quantum dot comprises a body and a shell layer coated on the body, the shell layer comprises polysiloxane, the body is connected with an X group through a mercapto group, the X group is connected with the polysiloxane, and the X group comprises at least one of a polar organic chain segment and a non-polar organic chain segment.

Further, in step S1, the reaction solution further includes a cation precursor.

Further, in the step S1, the reaction temperature is 100-320 ℃.

Further, in the step S2, the molar concentration of the acid or the base in the solution is 0.001 to 0.01M.

Further, in the step S2, the mass ratio of the quantum dots to the water in the solution is 1 (0.01-0.1);

further, in the step S2, the reaction temperature is 20-100 ℃.

Has the advantages that:

(1) the quantum dot comprises an organic ligand of a compound represented by a formula (1), wherein a siloxane end group in the organic ligand is easy to generate hydrolysis reaction under an acid or alkali environment to form polysiloxane to form an outer shell layer for coating a body, and the outer shell layer is firmly connected with the body sequentially through an X group and a sulfydryl group, so that the stability of the obtained core-shell quantum dot is effectively enhanced, and the core-shell quantum dot can be suitable for disperse systems with different polarities.

(2) According to the preparation method of the core-shell quantum dot, the organic ligand from the compound represented by the formula (1) on the quantum dot is hydrolyzed in an acid or alkali environment to prepare the outer shell layer containing polysiloxane, the process is simple, and the preparation method is green and environment-friendly and has good economic and social benefits.

Drawings

Fig. 1 is a time-dependent change of a core-shell quantum dot QY obtained in example 1 of the present application;

fig. 2 is a TEM image of the core-shell quantum dot obtained in example 1 of the present application;

fig. 3 is a diagram showing a state where core-shell quantum dots are dissolved in PGMEA in example 2 of the present application.

Detailed Description

The technical solutions in the examples of the present application will be described in detail below with reference to the embodiments of the present application. It should be noted that the described embodiments are only some embodiments of the present application, and not all embodiments. Unless otherwise defined, all terms (including technical and scientific terms) in the specification may be defined as commonly understood by one of ordinary skill in the art. Unless clearly defined, terms defined in a general dictionary may be undesirably or exaggeratedly explained. Furthermore, unless explicitly described to the contrary, the word "comprise" and variations such as "comprises" or "comprising" will be understood to imply the inclusion of stated elements (elements) but not the exclusion of any other elements (elements).

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.

It will be understood that when an element such as a layer, film, region or substrate is referred to as being "on" another element, it 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.

Furthermore, the singular includes the plural unless otherwise mentioned. As used herein, at least one of the terms "a", "an", "the" and "… …" do not denote a limitation of quantity, but are intended to include both the singular and the plural, unless the context clearly indicates otherwise. For example, "an element" has the same meaning as "at least one element" unless the context clearly dictates otherwise. "at least one" is not to be construed as limiting "a" or "an". "or" means "and/or". As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises" and/or "comprising," or variations thereof, when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

As mentioned in the background, the cadmium-free quantum dot is currently commonly used as InP, and the outermost layer of InP is usually coated with ZnSe or ZnS shell layer, which is easily oxidized and has poor quantum dot stability.

In this regard, the present application provides a quantum dot comprising a body comprising a group IIB-VIA compound or a group IIIA-VA compound; and an organic ligand derived from a compound represented by formula (1): r¹-X-Si(OR²)₃ (1)

The inventor finds that the organic ligand of the quantum dot is derived from the compound represented by the formula (1), the quantum dot provided by the application has the organic ligand derived from the compound represented by the formula (1), the sulfydryl at one end of the organic ligand is firmly connected with the body, the siloxane chain segment at the other end can be hydrolyzed to form an outer shell layer which is coated on the surface of the body and contains polysiloxane, and the outer shell layer is connected with the sulfydryl through an X group, so that the core-shell quantum dot with better stability is obtained.

In one embodiment of the present application, the mass percentage of the organic ligand in the quantum dot is 10-30%, so that the thickness of a shell layer formed on the surface of the quantum dot and containing polysiloxane is suitable, and the stability of the quantum dot is maximally improved while the content of the ligand is minimized.

In another embodiment of the present application, X includes at least one of an aliphatic segment, an aromatic segment, an amide segment, an ester segment, an ether segment, and a ketone segment, wherein the aliphatic segment and the aromatic segment facilitate the quantum dot to be dissolved in the non-polar solvent, and the amide segment, the ester segment, the ether segment, or the ketone segment facilitate the quantum dot to be better dissolved in the polar solvent, so that the quantum dot can be applied to different solution systems.

In yet another embodiment of the present application, R²Including at least one of hydrogen and alkyl.

In a preferred embodiment of the present application, R²Including at least one of hydrogen, methyl, ethyl, propyl, isopropyl, butyl, thereby making it easier for the organic ligands derived from the compound represented by formula (1) to hydrolyze to form a polysiloxane outer shell.

In another preferred embodiment of the present application, the molecular weight of the organic ligand is less than 500, so that the subsequent hydrolysis efficiency can be improved, the organic ligand is sufficiently hydrolyzed on the surface of the quantum dot to form an outer shell layer containing polysiloxane, and the stability of the core-shell quantum dot is further improved.

In the organic ligand of the quantum dot, sulfydryl and a cation precursor form a sulfide shell layer on the surface of a body, the sulfydryl of the sulfide shell layer is connected with an X group, the X group is connected with a siloxane group, the siloxane group is hydrolyzed and polymerized into a polysiloxane chain segment under the condition of acid or alkali, and the X is used as a bridging chain segment of the sulfydryl and the polysiloxane chain segment and is anchored at the outermost layer of the quantum dot at the moment, so that the solubility of the core-shell quantum dot is controlled.

The present application also provides a core-shell quantum dot, comprising: a body comprising a group IIB-VIA compound or a group IIIA-VA compound; and a skin layer comprising a polysiloxane; the body is connected with an X group through a mercapto group, the X group is connected with the polysiloxane, and the X group comprises at least one of a polar organic chain segment and a non-polar organic chain segment. The outer shell layer of the core-shell quantum dot comprises polysiloxane, the polysiloxane is good in stability in the environment, the structure of the core-shell quantum dot positioned inside the outer shell layer is effectively protected from water and oxygen, the stability of the core-shell quantum dot is remarkably improved while high quantum efficiency is kept, the polarity of the core-shell quantum dot can be changed as required, and the solution applicability of the core-shell quantum dot is better.

s1, reacting the initial quantum dots and the compound represented by the formula (1) to form the quantum dots;

the cation on the initial quantum dot will coordinate with the thiol group in the compound represented by formula (1) to form the above quantum dot.

In the present application, the initial quantum dots may be prepared by any known method or may be commercially available. For example, the initial quantum dots may include group II-VI compounds, group III-V compounds, group IV-VI compounds, group I-III-VI compounds, group I-II-IV-VI compounds, perovskite compounds, carbon quantum dots, or combinations thereof. For example, the group II-VI compounds may include: CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, CdSeS, CdSeTe, CdSSte, 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, HgZnSnZnSTe, or combinations thereof. The II-VI compound can further include a group III metal. The group III-V compounds may include: GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaAs, GaSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, ZnP, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InInInInInInNP, InAlNAs, InNSb, InAlPAs, InAlPSb, or combinations thereof. The III-V compound may further include a group II metal (e.g., InZnP). The group IV-VI compounds 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 group I-III-VI compounds may include CuInSe2, CuInS2, CuInGaSe, and CuInGaS, but are not limited thereto. Examples of the group I-II-IV-VI compounds may include, but are not limited to, CuZnSnSe and CuZnSnS.

The initial quantum dot may further be of a core-shell structure, for example, the initial quantum dot may include a core of the nanocrystal and a shell disposed on at least a portion of a surface of the nanocrystal and comprising a composition different from the core of the nanocrystal. At the interface between the core and the shell, there may or may not be an alloyed interlayer. The alloyed layer may include a homogeneous alloy. In addition, the shell may comprise a multi-layer shell having at least two layers, wherein adjacent layers have different compositions from each other. In the multilayer shell, each layer may have a single composition. In the multilayer shell, each layer may have an alloy. In the multilayer shell, each layer may have a concentration gradient that varies in a radial direction according to the composition of the nanocrystal.

In the initial quantum dot of the core-shell structure, the material of the shell may have a band gap energy greater than that of the material of the core, but is not limited thereto. The material of the shell may have a bandgap energy that is less than the bandgap energy of the material of the core. In the case of the multi-layer shell, the band gap energy of the outermost layer material of the shell may be larger than the band gap of the material of the core and the inner layer material of the shell (layer closer to the core). In the case of the multilayer shell, the nanocrystals of the respective layers are selected to have appropriate band gap energies, thereby effectively exhibiting a quantum confinement effect.

In addition, the particle size of the initial quantum dot may have a size of about 1nm to about 100 nm. For example, the initial quantum dots may have a particle size of about 1nm to about 50nm, such as from 2nm to 20 nm. The shape of the initial quantum dot is a shape generally used in the art, and is not particularly limited.

It is understood that the structure of the bulk of the present application is derived from the initial quantum dots, e.g. the structure of the bulk of the present application is the core structure or the core-shell structure of the initial quantum dots.

The utility model provides a body passes through X group and is connected with the shell layer, and the nucleocapsid quantum dot stable in structure of formation, water oxygen barrier nature is good, places the quantum efficiency of nucleocapsid quantum dot after one section and also does not reduce, increases nucleocapsid quantum dot life.

In one embodiment of the preparation method of the present application, in step S1, the mixed solution further includes a cation precursor, the cation precursor reacts with the compound represented by formula (1) to form a sulfide shell on the bulk, the cation precursor is preferably a zinc precursor, the zinc precursor and the thiol group of the compound represented by formula (1) and the zinc precursor form a ZnS shell on the surface of the bulk to protect the cations of the bulk from corrosion, and SiOR²And the chain segment is hydrolyzed to form polysiloxane, a polysiloxane shell layer is formed on the surface of the ZnS shell layer, and the polysiloxane shell layer is connected with the ZnS shell layer through an X group.

In another embodiment of the preparation method of the present application, in step S1, the reaction temperature is 100 to 240 ℃, so that the compound represented by formula (1) can be better coordinated and bonded to the surface of the initial quantum dot.

In a preferred embodiment of the present application, the reaction time is not less than 10min, so that the core-shell quantum dots have more uniform particle size and better stability, and the reaction time is preferably 0.5-2 h.

In another embodiment of the preparation method of the present application, in step S2, the solvent of the solution is water, and the molar concentration of the acid or the base is 0.001 to 0.01M, so that the organic ligand derived from the compound represented by formula (1) can be effectively hydrolyzed to form an outer shell layer containing polysiloxane, without destroying the quantum efficiency of the core-shell quantum dot.

In a preferred embodiment of the present application, the acid is at least one of acetic acid, hydrochloric acid, nitric acid, and sulfuric acid, which has good water solubility and is beneficial to promoting the hydrolysis reaction.

In another preferred embodiment of the present application, the base is at least one of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and sodium bicarbonate, so that the reaction rate of hydrolyzing the organic ligand derived from the compound represented by formula (1) to form an outer shell layer comprising polysiloxane is more preferable.

In still another embodiment of the preparation method of the present application, in step S2, the mass ratio of the quantum dot to the water is 1 (0.01 to 0.1), so as to facilitate sufficient hydrolysis of the organic ligand derived from the compound represented by formula (1) into an outer shell layer containing polysiloxane, and further not to destroy the quantum dot body due to an excessively large amount of water, so that the obtained core-shell quantum dot has higher stability.

In the present application, a solution containing water, acid or alkali may be added in a form of dropping to the quantum dots, thereby effectively controlling the formation rate of the outer shell layer containing polysiloxane to obtain an outer shell layer having a uniform thickness.

In another embodiment of the preparation method of the present application, in step S2, the reaction temperature is 20 to 100 ℃, so that the organic ligand from the compound represented by formula (1) can effectively participate in the reaction without decomposition of the organic ligand, and volatilization of acid or alkali is effectively avoided, so that the hydrolysis reaction is more sufficient, and the core-shell quantum dot with more excellent stability is obtained.

In a preferred embodiment of the application, the reaction time is 0.5-2 h, so that the preparation efficiency of the core-shell quantum dot is improved, and the reaction can be fully carried out.

Quantum dot compositions, display 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.

Example 1

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 220 ℃, and adding 1g of InP/ZnSe/ZnS initial quantum dots; 4mmol of HS- (CH) are added dropwise₂)₅-Si(OCH₃)₃And the addition is finished in 1 hour. And cooling to 30 ℃, slowly adding 0.05mL of 0.005M ammonia water solution, adding the solution for 1 hour, purifying, and dissolving the purified solution in n-heptane to obtain the core-shell quantum dot.

Example 2

Argon is filled into 20mL of ODE, the temperature is raised to 220 ℃, and 1g of InP/ZnSe/ZnS initial quantum dots are added; 4mmol of HS- (CH) are added dropwise₂)₅-Si(OCH₃)₃And the addition is finished in 1 hour. And cooling to 30 ℃, slowly adding 0.05mL of 0.005M ammonia water solution, adding the solution for 1 hour, purifying, and dissolving the purified solution in n-heptane to obtain the core-shell quantum dot.

Example 3

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 220 ℃, and adding 1g of InP/ZnSe/ZnS initial quantum dots; 4mmol of HS- (CH) are added dropwise₂CH₂O)₆-Si(OCH₃)₃And the addition is finished in 1 hour. The temperature is reduced to 30 ℃, 0.05mL of 0.005M ammonia solution is slowly added, and the addition is finished for 1 hour. And dissolving the purified product into PGMEA to obtain the core-shell quantum dot.

Example 4

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 220 ℃, and adding 1g of InP/ZnSe/ZnS initial quantum dots; 4mmol of HS-PH- (NH) are added dropwise₂)-Si(OCH₃)₃And the addition is finished in 1 hour. Cooling to 30 ℃, slowly adding 0.005M ammonia water 0.05mL for 1 hour. And dissolving the purified product into n-heptane to obtain the core-shell quantum dot.

Example 5

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 220 ℃, and adding 1g of InP/ZnSe/ZnS initial quantum dots; 4mmol of HS- (CH) are added dropwise₂)₅-Si(OCH₃)₃And the addition is finished in 1 hour. And cooling to 30 ℃, slowly adding 0.005M hydrochloric acid 0.05mL for 1 hour, and dissolving in n-heptane after purification to obtain the structural quantum dots.

Example 6

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 220 ℃, and adding 1g of InP/ZnSe/ZnS initial quantum dots; 4mmol of HS- (CH) are added dropwise₂)₅-Si(OCH₃)₃And the addition is finished in 1 hour. And cooling to 80 ℃, slowly adding 0.05mL of 0.005M ammonia water solution for 1 hour, and dissolving the mixture into n-heptane after purification to obtain the core-shell quantum dot.

Example 7

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 220 ℃, and adding 1g of InP/ZnSe/ZnS initial quantum dots; 4mmol of HS- (CH) are added dropwise₂)₅-Si(OCH₃)₃And the addition is finished in 1 hour. The temperature is reduced to 30 ℃, 0.1mL of 0.005M ammonia solution is slowly added, and the addition is finished within 1 hour. And dissolving the purified product into n-heptane to obtain the core-shell quantum dot.

Example 8

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 280 ℃, and adding 1g of InP/ZnSe/ZnS initial quantum dots; 4mmol of HS- (CH) are added dropwise₂)₅-Si(OCH₃)₃And the addition is finished in 1 hour. The temperature is reduced to 30 ℃, 0.05mL of 0.005M ammonia solution is slowly added, and the addition is finished for 1 hour. And dissolving the purified product into n-heptane to obtain the core-shell quantum dot.

Example 9

Adding 4mmol zinc oleate into 20mL ODE, vacuumizing at 120 deg.C for 1 hr, introducing argon, heating to 220 deg.CAdding 1g of ZnSe/ZnS initial quantum dots at the temperature of DEG C; 4mmol of HS- (CH) are added dropwise₂)₅-Si(OCH₃)₃And the addition is finished in 1 hour. The temperature is reduced to 30 ℃, 0.05mL of 0.005M ammonia solution is slowly added, and the addition is finished for 1 hour. And dissolving the purified product into n-heptane to obtain the core-shell quantum dot.

Example 10

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 220 ℃, and adding 1g of CdSe/ZnS initial quantum dots; 4mmol of HS- (CH) are added dropwise₂)₅-Si(OCH₃)₃And the addition is finished in 1 hour. The temperature is reduced to 30 ℃, 0.05mL of 0.005M ammonia solution is slowly added, and the addition is finished for 1 hour. And dissolving the purified product into n-heptane to obtain the core-shell quantum dot.

Comparative example 1

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 220 ℃, and adding 1g of InP/ZnSe/ZnS initial quantum dots; 4mmol of HS- (CH) are added dropwise₂)₅-Si(OCH₃)₃And the addition is finished in 1 hour. And dissolving the purified product into n-heptane to obtain the core-shell quantum dot.

Comparative example 2

Adding 4mmol of zinc oleate into 20mL of ODE, vacuumizing at 120 ℃ for 1 hour, introducing argon, heating to 220 ℃, and adding 1g of InP/ZnSe/ZnS initial quantum dots; 4mmol of dodecanethiol are added dropwise over 1 hour. The temperature is reduced to 30 ℃, 0.05mL of 0.005M ammonia solution is slowly added, and the addition is finished for 1 hour. And dissolving the purified product into n-heptane to obtain the core-shell quantum dot.

Preparing the initial quantum dots and the core-shell quantum dots of the examples 1 to 10 and the comparative examples 1 to 2 into 100mg/mL solutions, measuring the quantum efficiency (QY) by taking 10mL of each solution, and measuring the quantum efficiency (QY) after placing 10mL of the core-shell quantum dots for 300 days; the change of the core-shell quantum dot QY obtained in the example 1 along with time is plotted as shown in FIG. 1, and the core-shell quantum dot QY is basically maintained at about 80%; TEM characterization of the core-shell quantum dots is carried out by adopting a Tecnai G2F 20 transmission electron microscope, as shown in FIG. 2, wherein a dark part 11 is a quantum dot body, and a light part 12 is an outer shell layer containing polysiloxane; the core-shell quantum dots in example 2 are dissolved in PGMEA, as shown in fig. 3, the core-shell quantum dots have good solubility and good solution dispersibility.

TABLE 1 initial Quantum dots, core-shell Quantum dots QY cases of examples 1 to 10, comparative examples 1 to 2

As can be seen from the above table, compared with comparative examples 1 to 2, the core-shell quantum dots of embodiments 1 to 10 of the present application still maintain very high quantum efficiency after 300 days, which indicates that the core-shell quantum dots prepared by the technical scheme of the present application have good stability, and are beneficial to promoting the commercial application of cadmium-free quantum dots.

Although the present disclosure has been described and illustrated in greater detail by the inventors, it should be understood that modifications and/or alterations to the above-described embodiments, or equivalent substitutions, will be apparent to those skilled in the art without departing from the spirit of the disclosure, and that no limitations to the present disclosure are intended or should be inferred therefrom.

Claims

1. A quantum dot, comprising:

a body comprising a group IIB-VIA compound or a group IIIA-VA compound; and

an organic ligand derived from a compound represented by formula (1): r¹-X-Si(OR²)₃(1)

2. The quantum dot according to claim 1, wherein the organic ligand is contained in the quantum dot in an amount of 10 to 50% by mass.

3. The quantum dot of claim 1, wherein R is²Including at least one of hydrogen and alkyl.

4. A core-shell quantum dot, comprising:

a body comprising a group IIB-VIA compound or a group IIIA-VA compound; and

a casing layer comprising a polysiloxane;

5. A preparation method of the core-shell quantum dot is characterized by comprising the following steps:

s1, reacting the initial quantum dots with a compound represented by formula (1) to form the quantum dots according to any one of claims 1 to 3;

6. The method for preparing a core-shell quantum dot according to claim 5, wherein in step S1, the reaction solution further includes a cation precursor.

7. The method for preparing the core-shell quantum dot according to claim 5, wherein in the step S1, the reaction temperature is 100-320 ℃.

8. The method for preparing a core-shell quantum dot according to claim 5, wherein in the step S2, the molar concentration of the acid or the base in the solution is 0.001 to 0.01M.

9. The method for preparing a core-shell quantum dot according to claim 5, wherein in the step S2, the mass ratio of the quantum dot to the water in the solution is 1 (0.01-0.1).

10. The preparation method of the core-shell quantum dot according to any one of claims 5 to 9, wherein in the step S2, the reaction temperature is 20-100 ℃.