阅读说明：本技术 无镉量子点及其制备方法 (Cadmium-free quantum dot and preparation method thereof ) 是由 高静 汪均 谢阳腊 乔培胜 余文华 李光旭 苏叶华 于 2018-08-09 设计创作，主要内容包括：本发明提供了一种无镉量子点及其制备方法。该制备方法包括以下步骤：S1,将含III族元素前体、V族元素前体和第一配体的第一原料混合反应,得到III-V族半导体纳米团簇；S2,将含II族元素前体、VI族元素前体和第二配体的第二原料混合反应,得到II-VI族半导体纳米团簇；S3,将III-V族半导体纳米团簇与II-VI族半导体纳米团簇混合反应,得到III-V-II-VI族量子点。上述方法通过将两种不稳定态的团簇的反应形成形貌均一的无镉量子点,通过实验证明该无镉量子点不仅能够具有较窄的半峰宽,还能够具有较高的发光效率。(The invention provides a cadmium-free quantum dot and a preparation method thereof. The preparation method comprises the following steps: s1, mixing and reacting the first raw material containing the III group element precursor, the V group element precursor and the first ligand to obtain the III-V group semiconductor nanocluster; s2, mixing and reacting a second raw material containing a group II element precursor, a group VI element precursor and a second ligand to obtain a group II-VI semiconductor nanocluster; and S3, mixing and reacting the III-V group semiconductor nanoclusters and the II-VI group semiconductor nanoclusters to obtain the III-V-II-VI group quantum dots. According to the method, the cadmium-free quantum dots with uniform shapes are formed by the reaction of clusters of two unstable states, and experiments prove that the cadmium-free quantum dots not only have narrow half-peak widths, but also have high luminous efficiency.)

1. A preparation method of cadmium-free quantum dots is characterized by comprising the following steps:

s1, mixing and reacting the first raw material containing the III group element precursor, the V group element precursor and the first ligand to obtain the III-V group semiconductor nanocluster;

s2, mixing and reacting a second raw material containing a group II element precursor, a group VI element precursor and a second ligand to obtain a group II-VI semiconductor nanocluster;

and S3, mixing and reacting the III-V group semiconductor nanoclusters and the II-VI group semiconductor nanoclusters to obtain the III-V-II-VI group quantum dots.

2. The method of claim 1, wherein the group III-V semiconductor nanoclusters are InP clusters, InAs clusters, doped InP clusters, or doped InAs clusters.

3. The method of manufacturing according to claim 2, wherein the step of forming the doped InP cluster or the doped InAs cluster comprises:

doping the InP cluster by adopting a first cation dopant to form the doped InP cluster, or doping the InAs cluster by adopting a first cation dopant to form the doped InAs cluster; the first cationic dopant is selected from any one or more of Zn, Mg, Ca, Sr, Al, Zr, Fe, Ti, Cr, Si and Ni.

4. The method of manufacturing according to claim 1, wherein the II-VI semiconductor nanoclusters are ZnSe nanoclusters, ZnS nanoclusters, doped ZnSe nanoclusters, or doped ZnS nanoclusters.

5. The method of claim 4, wherein the step of forming the doped ZnSe cluster or the doped ZnS nanocluster includes:

doping the ZnSe nanocluster by using a second cation dopant to form the doped ZnSe cluster, or doping the ZnS nanocluster by using a second cation dopant to form the doped ZnS nanocluster; the cationic second dopant is selected from any one or more of Mg, Ca, Sr, Al, Zr, Fe, Ti, Cr, Si and Ni.

6. The method according to claim 1, wherein the group VI element precursor is a selenium precursor, and preferably the selenium precursor is a suspension of Se-ODE, a solution of Se-ODE, or selenium alkylphosphinate.

7. The production method according to any one of claims 1 to 3, wherein the molar ratio of the group III element precursor to the group V element precursor is 50:1 to 1:50, preferably 10:1 to 1: 10.

8. The production method according to any one of claims 1, 4, 5 and 6, wherein the molar ratio of the group II element precursor to the group VI element precursor is 50:1 to 1:50, preferably 20:1 to 1: 5.

9. The method according to claim 1, characterized in that after the step S3, the method further comprises the steps of:

coating a II-VI shell layer on the surface of the III-V-II-VI quantum dot to form a III-V-II-VI/II-VI core-shell quantum dot, preferably mixing and reacting the III-V semiconductor nanocluster with a first part in the II-VI semiconductor nanocluster to obtain the III-V-II-VI quantum dot core, and taking a second part in the II-VI semiconductor nanocluster as a shell layer of the III-V-II-VI quantum dot to form the III-V-II-VI/II-VI core-shell quantum dot, wherein the first part and the second part have different types.

10. The production method according to any one of claims 1 to 3, wherein the reaction temperature in the step S1 is 30 to 200 ℃.

11. The method according to any one of claims 1 to 6, wherein the reaction temperature in the step S2 is 100 to 280 ℃.

12. A cadmium-free quantum dot, which is prepared by the preparation method of any one of claims 1 to 11.

13. A cadmium-free quantum dot composition, comprising the cadmium-free quantum dot prepared by the preparation method of any one of claims 1 to 11.

14. An optoelectronic device comprising the cadmium-free quantum dot prepared by the preparation method of any one of claims 1 to 11.

Technical Field

The invention relates to the technical field of semiconductors, in particular to a cadmium-free quantum dot and a preparation method thereof.

Background

The quantum dots are also called semiconductor nanocrystals, and have the advantages of adjustable light-emitting wavelength, high light-emitting efficiency, good stability and the like, so that the quantum dots are widely applied to the fields of display, illumination, biology, solar cells and the like. In recent years, research on II-VI group quantum dot materials containing CdSe, CdS and the like has been greatly advanced, the efficiency, half-peak width, stability and other properties of the quantum dot materials are greatly improved, and the quantum dot materials are applied to the fields of display, biology and the like. However, since Cd is a toxic heavy metal, the european union "legislation on chemical registration, evaluation, permission and restriction" (REACH for short) strictly regulates the Cd content in goods entering the market, and its wide application is limited, so people never give up on research on environment-friendly cadmium-free quantum dots. How to improve the performance of the cadmium-free quantum dots is always the key point and the difficulty of research. In cadmium-free quantum dots, III-V group InP-based quantum dots become a research hotspot and are expected to replace Cd-containing quantum dots.

Disclosure of Invention

The invention mainly aims to provide a cadmium-free quantum dot and a preparation method thereof, and aims to solve the problems that the cadmium-free quantum dot in the prior art is low in luminous efficiency and large in luminous half-peak width.

In order to achieve the above object, according to an aspect of the present invention, there is provided a method for preparing a cadmium-free quantum dot, including the steps of: s1, mixing and reacting the first raw material containing the III group element precursor, the V group element precursor and the first ligand to obtain the III-V group semiconductor nanocluster; s2, mixing and reacting a second raw material containing a group II element precursor, a group VI element precursor and a second ligand to obtain a group II-VI semiconductor nanocluster; and S3, mixing and reacting the III-V group semiconductor nanoclusters and the II-VI group semiconductor nanoclusters to obtain the III-V-II-VI group quantum dots.

Further, the group III-V semiconductor nanoclusters are InP clusters, InAs clusters, doped InP clusters, or doped InAs clusters.

Further, the step of forming a doped InP cluster or a doped InAs cluster comprises: doping the InP cluster by adopting a first cation dopant to form a doped InP cluster, or doping the InAs cluster by adopting the first cation dopant to form a doped InAs cluster; the first cationic dopant is selected from any one or more of Zn, Mg, Ca, Sr, Al, Zr, Fe, Ti, Cr, Si and Ni.

Further, the II-VI semiconductor nanoclusters are ZnSe nanoclusters, ZnS nanoclusters, doped ZnSe nanoclusters, or doped ZnS nanoclusters.

Further, the step of forming doped ZnSe clusters or doped ZnS nanoclusters includes: doping the ZnSe nanocluster by using a second cation dopant to form a doped ZnSe cluster, or doping the ZnS nanocluster by using the second cation dopant to form a doped ZnS nanocluster; the cationic second dopant is selected from any one or more of Mg, Ca, Sr, Al, Zr, Fe, Ti, Cr, Si and Ni.

Further, the group VI element precursor is a selenium precursor, and preferably the selenium precursor is a suspension of Se-ODE, a solution of Se-ODE, or an alkyl phosphine selenium.

Further, the molar ratio of the group III element precursor to the group V element precursor is 50:1 to 1:50, preferably 10:1 to 1: 10.

Further, the molar ratio of the group II element precursor to the group VI element precursor is 50:1 to 1:50, preferably 20:1 to 1: 5.

Further, after step S3, the preparation method further includes the steps of: the method comprises the steps of coating a II-VI shell layer on the surface of a III-V-II-VI quantum dot to form the III-V-II-VI/II-VI quantum dot, preferably mixing and reacting a III-V semiconductor nanocluster with a first part of the II-VI semiconductor nanocluster to obtain a III-V-II-VI quantum dot core, and taking a second part of the II-VI semiconductor nanocluster as a shell layer of the III-V-II-VI quantum dot to form the III-V-II-VI/II-VI group core-shell quantum dot, wherein the first part and the second part have different types.

Further, the reaction temperature in step S1 is 30-200 ℃.

Further, the reaction temperature in step S2 is 100-280 ℃.

According to another aspect of the invention, the cadmium-free quantum dot is prepared by adopting the preparation method.

According to another aspect of the invention, a cadmium-free quantum dot composition is also provided, which comprises the cadmium-free quantum dot prepared by the preparation method.

According to another aspect of the invention, a photoelectric device is also provided, which comprises the cadmium-free quantum dot prepared by the preparation method.

The technical scheme of the invention provides a preparation method of the cadmium-free quantum dot, the method forms the cadmium-free quantum dot with uniform appearance by the reaction of two unstable state clusters, and experiments prove that the cadmium-free quantum dot not only has narrower half peak width, but also has higher luminous efficiency.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 shows a schematic flow chart of a preparation method of a cadmium-free quantum dot provided by the invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged under appropriate circumstances in order to facilitate the description of the embodiments of the invention herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

As described in the background, the quantum dot without cadmium in the prior art has low light efficiency and large half-width of light emission. In order to solve the above technical problems, the present invention provides a method for preparing cadmium-free quantum dots, as shown in fig. 1, comprising the following steps: s1, mixing and reacting the first raw material containing the III group element precursor, the V group element precursor and the first ligand to obtain the III-V group semiconductor nanocluster; s2, mixing and reacting a second raw material containing a group II element precursor, a group VI element precursor and a second ligand to obtain a group II-VI semiconductor nanocluster; and S3, mixing and reacting the III-V group semiconductor nanoclusters and the II-VI group semiconductor nanoclusters to obtain the III-V-II-VI group quantum dots.

In the art, the group III element in the group III element precursor is generally referred to as a group III element, the group V element in the group V element precursor is generally referred to as a group V element, the group II element in the group II element precursor is generally referred to as a group II subgroup element, and the group VI element in the group VI element precursor is generally referred to as a group VI element.

By adopting the preparation method of the cadmium-free quantum dot, the cadmium-free quantum dot with uniform appearance is formed by the reaction of clusters of two unstable states, and experiments prove that the cadmium-free quantum dot not only has narrower half-peak width, but also has higher luminous efficiency.

In the above step S1, the III-V semiconductor nanoclusters to be used are preferably an InP cluster, an InAs cluster, a doped InP cluster, or a doped InAs cluster. More preferably, the step of forming the doped InP cluster or the doped InAs cluster includes: doping the InP cluster by adopting a first cation dopant to form a doped InP cluster, or doping the InAs cluster by adopting the first cation dopant to form a doped InAs cluster; the first cationic dopant may be selected from any one or more of Zn, Mg, Ca, Sr, Al, Zr, Fe, Ti, Cr, Si and Ni. The InP-based quantum dots in the prior art have the problems of low fluorescence quantum yield, large luminescence half-peak width (low color purity) and poor light, heat and water stability, and the method for doping the InP clusters can further improve the fluorescence quantum yield and stability of the quantum dots.

In the above step S2, preferably, the group VI element precursor is a selenium precursor. The person skilled in the art can select the present selenium precursor according to the actual need. More preferably, the selenium precursor is a suspension of Se-ODE, a solution of Se-ODE or a selenium alkylphosphinate.

In the above-described step S2, preferably, the II-VI semiconductor nanoclusters are ZnSe nanoclusters, ZnS nanoclusters, doped ZnSe nanoclusters, or doped ZnS nanoclusters. More preferably, the step of forming the doped ZnSe cluster or the doped ZnS nanocluster includes: doping the ZnSe nanocluster by using a second cation dopant to form a doped ZnSe cluster, or doping the ZnS nanocluster by using the second cation dopant to form a doped ZnS nanocluster; the second cationic dopant may be selected from any one or more of Mg, Ca, Sr, Al, Zr, Fe, Ti, Cr, Si and Ni. Similarly, the ZnSe-based quantum dots in the prior art also have the problems of low fluorescence quantum yield, large luminescence half-peak width (low color purity) and poor light, heat and water stability, and the doping of the ZnSe cluster by adopting the method can further improve the fluorescence quantum yield and stability of the quantum dots.

In the above production method of the present invention, the molar ratio of the group III element precursor to the group V element precursor is preferably 50:1 to 1:50, and more preferably 10:1 to 1: 10. Preferably, the molar ratio of the group II element precursor to the group VI element precursor is 50:1 to 1:50, more preferably 20:1 to 1: 5.

In a preferred embodiment, after the step S3, the preparation method further includes the steps of: and coating the II-VI shell layer on the surface of the III-V-II-VI quantum dot to form the III-V-II-VI/II-VI quantum dot, more preferably, mixing the III-V semiconductor nanocluster with a first part of the II-VI semiconductor nanocluster for reaction to obtain a III-V-II-VI quantum dot core, and taking a second part of the II-VI semiconductor nanocluster as the shell layer of the III-V-II-VI quantum dot to form the III-V-II-VI/II-VI group core-shell quantum dot. The II-VI shell layer can improve the stability of the cadmium-free quantum dot, wherein the first part and the second part are of different types.

And coating the other part of the II-VI semiconductor nanoclusters on the surface of the III-V-II-VI quantum dot core layer to form a shell layer, thereby forming the cadmium-free quantum dot. A part of II-VI semiconductor nanoclusters are coated on the surface of the III-V-II-VI quantum dot core layer to serve as a shell layer, so that the stability of the cadmium-free quantum dot is greatly improved.

In the preparation method of the present invention, preferably, the reaction temperature in step S1 is 30 to 200 ℃; also, the reaction temperature in step S2 is preferably 100 to 280 ℃. By optimizing the reaction temperature in steps S1 and S2, the efficiency of the process of generating the above-described group III-V semiconductor nanoclusters and the above-described group II-VI semiconductor nanoclusters by reacting the first raw material and the second raw material can be effectively improved.

According to another aspect of the application, a cadmium-free quantum dot is provided, and the cadmium-free quantum dot is prepared by adopting the preparation method. Experiments prove that the cadmium-free quantum dot not only has narrower half-peak width, but also has higher luminous efficiency.

According to another aspect of the present application, a cadmium-free quantum dot composition is provided, which comprises the cadmium-free quantum dot prepared by the above preparation method. When the composition is used for specific application, the composition also has the application advantages because the cadmium-free quantum dots not only have narrower half-peak width, but also have higher luminous efficiency.

According to another aspect of the present application, there is provided an optoelectronic device comprising cadmium-free quantum dots as electroluminescent material or photoluminescent material. The optoelectronic device may be, in particular, an electroluminescent display device, a photoluminescent display device, an image sensor or a solar cell.

The present invention is described in further detail below with reference to specific examples, which are not to be construed as limiting the scope of the invention as claimed.