Quantum dot, preparation method thereof, synthesis system and light-emitting device

Abstract

The invention discloses a quantum dot, a preparation method thereof, a synthesis system and a luminescent device. The preparation method comprises the following steps: providing a precursor solution for synthesizing nanoparticles; providing a micro-reaction channel, wherein the micro-reaction channel comprises a first heating section and a second heating section; the precursor solution is injected into a micro-reaction channel, the precursor solution sequentially flows through the first heating section and the second heating section, nano-particles are obtained, and the quantum dots comprise the nano-particles; wherein the first heating section adopts microwave heating. The invention aims to solve the problem of poor uniformity of quantum dots prepared by the existing quantum dot synthesis method.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a quantum dot, a preparation method thereof, a synthesis system and a light-emitting device. Background Art

[0002] Quantum dots (QDs) are nanocrystalline particles with a radius smaller than or close to the Bohr exciton radius, which have quantum confinement effects. Their special electronic structure and optoelectronic properties have made them widely studied in the fields of photovoltaics and light-emitting displays.

[0003] The current mainstream method for synthesizing quantum dots is to mix the precursor material of the quantum dots and the solvent in batches and then heat them to make quantum dots; however, it is found in the actual production process that the quantum dots produced in this way often have poor uniformity. Summary of the invention

[0004] In view of this, the present application provides a quantum dot and a preparation method and a synthesis system and a light-emitting device, aiming to solve the problem of poor uniformity of quantum dots produced by existing quantum dot synthesis methods.

[0005] The embodiment of the present application is implemented as follows:

[0006] In a first aspect, the present application provides a method for preparing quantum dots, comprising the following steps:

[0007] Providing a precursor solution for synthesizing nanoparticles;

[0008] Providing a micro-reaction channel, the micro-reaction channel comprising a first heating section and a second heating section;

[0009] Injecting the precursor solution into the micro-reaction channel, the precursor solution sequentially flows through the first heating section and the second heating section to obtain nanoparticles, wherein the quantum dots include the nanoparticles;

[0010] Wherein, the first heating section adopts microwave heating.

[0011] Optionally, in some embodiments of the present application, during the microwave heating, the microwave power is 400-1100 W; and / or,

[0012] The residence time of the precursor solution in the first heating section is controlled to be 2 to 9 seconds.

[0013] Optionally, in some embodiments of the present application, the flow rate of the precursor solution in the first heating section is 0.01 to 10 ml / min.

[0014] Optionally, in some embodiments of the present application, the heating temperature of the second heating section is 200-290° C.; and / or,

[0015] Controlling the residence time of the precursor solution in the second heating section to be 10 to 60 minutes; and / or,

[0016] The temperature of the first heating section is greater than the temperature of the second heating section.

[0017] Optionally, in some embodiments of the present application, the temperature difference between the first heating section and the second heating section is 20-40°C.

[0018] Optionally, in some embodiments of the present application, the quantum dots include one of single structure quantum dots and core-shell structure quantum dots;

[0019] When the quantum dot is a single-structure quantum dot, the nanoparticles constitute the quantum dot;

[0020] When the quantum dots are core-shell structured quantum dots, the quantum dots are composed of the nanoparticles and a shell covering the nanoparticles.

[0021] Optionally, in some embodiments of the present application, the micro-reaction channel further comprises a feeding section and a third heating section which are connected in sequence, wherein the inlet of the feeding section is connected to the outlet of the second heating section;

[0022] When the quantum dots are core-shell structure quantum dots, after the step of injecting the precursor solution into the micro-reaction channel and the precursor solution sequentially flowing through the first heating section and the second heating section to obtain nanoparticles, the step further includes:

[0023] providing a shell precursor solution;

[0024] The shell precursor solution is injected into the feeding section and mixed with the liquid output from the second heating section to form a mixed solution. The mixed solution flows through the third heating section to form a shell on the surface of the nanoparticles to obtain core-shell structured quantum dots.

[0025] In a second aspect, the present application also proposes a quantum dot, including a quantum dot prepared by the preparation method.

[0026] Optionally, in some embodiments of the present application, the quantum dots include one of single-structure quantum dots and core-shell structure quantum dots; the material of the single-structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots are independently selected from at least one of II-VI group compounds, IV-VI group compounds, III-V group compounds and I-III-VI group compounds; the II-VI group compounds are selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdS At least one of Te, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe; the IV-VI group compound is selected from SnS, SnSe, SnTe, Pb At least one of S, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the III-V group compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlN At least one of Sb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; the I-III-VI group compound is selected from at least one of CuInS2, CuInSe2 and AgInS2.

[0027] In a third aspect, the present application further proposes a light-emitting device, comprising a light-emitting layer, wherein the material of the light-emitting layer comprises quantum dots prepared by the preparation method described above, or the quantum dots described above.

[0028] In a fourth aspect, the present application also proposes a quantum dot synthesis system, comprising a microfluidic reaction device and a microwave heating device, wherein the microfluidic reaction device comprises a microreaction channel, wherein the microreaction channel has a plurality of channel segments, wherein the plurality of channel segments comprise a first heating segment and a second heating segment sequentially arranged along a material conveying direction, and the microwave heater is arranged corresponding to the first heating segment for heating the first heating segment.

[0029] Optionally, in some embodiments of the present application, the plurality of channel sections further include a feeding section and a third heating section that are connected in sequence, wherein the inlet of the feeding section is connected to the outlet of the second heating section; and / or,

[0030] The synthesis system further comprises a first heater, which is arranged corresponding to the second heating section and is used to heat the second heating section; and / or,

[0031] The microfluidic reaction device further comprises a plurality of injection pipes, and the outlets of the plurality of injection pipes are all connected to the inlet of the micro reaction channel.

[0032] Optionally, in some embodiments of the present application, the synthesis system further includes a second heater, which is arranged corresponding to the third heating section and is used to heat the third heating section; and / or,

[0033] The feeding section has a feeding port; the microfluidic reaction device also includes at least one feeding pipeline, and the outlet of the at least one feeding pipeline is connected to the feeding port of the feeding section.

[0034] In the technical solution provided in the present application, a microfluidic method is used to inject a first precursor solution to synthesize quantum dots, which can continuously and in large quantities synthesize quantum dots and achieve precise control of fluid reactions at the micrometer level, which helps to improve the synthesis efficiency of the reaction; at the same time, microwave heating is used in the first heating section of the microreaction channel, which can heat the precursor solution in a very short time and very evenly, so that the same section of fluid can nucleate at the same time, thereby producing quantum dots of uniform size; in addition, microwave heating is used only in the first heating section, which can reduce energy consumption and production costs while improving the uniformity of quantum dot size. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1It is a schematic diagram of a process for preparing quantum dots proposed in one embodiment of the present application;

[0037] Figure 2 is a schematic flow chart of a method for preparing quantum dots proposed in another embodiment of the present application;

[0038] Figure 3 is a schematic flow chart of a method for preparing quantum dots proposed in another embodiment of the present application;

[0039] Figure 4 is a schematic structural diagram of a light-emitting device proposed in one embodiment of the present application;

[0040] Figure 5 It is a schematic diagram of the structure of a quantum dot synthesis system proposed in an embodiment of the present application;

[0041] Reference numerals:

[0042] 100-light-emitting device; 10-anode; 20-light-emitting layer; 30-electron transport layer; 40-cathode; 50-hole transport layer; 60-hole injection layer; 1-injection pump; 2-feeding pump; 301-first heating section, 302-second heating section, 303-feeding section, 304-third heating section. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0044] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the specification of this application, the term "including" means "including but not limited to".

[0045] Various embodiments of the present application may be presented 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 understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0046] In this application, "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0047] In the present application, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0048] The embodiment of the present application proposes a quantum dot and a preparation method thereof, wherein the quantum dot can be a quantum dot of a single structure or a quantum dot of a core-shell structure; the size of the quantum dot has good uniformity, and according to statistics of transmission electron microscopy (TEM) characterization, the size difference of the quantum dot is less than or equal to 10%.

[0049] Specifically, the quantum dots can be selected from but not limited to single-structure quantum dots and core-shell structure quantum dots. When the quantum dots are selected from single-structure quantum dots, the material of the single-structure quantum dots is selected from at least one of II-VI compounds, IV-VI compounds, III-V compounds and I-III-VI compounds; the II-VI compounds are selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, Cd At least one of ZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe; the IV-VI group compound is selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnST e, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; the III-V group compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb , at least one of InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; the I-III-VI group compound is selected from at least one of CuInS2, CuInSe2 and AgInS2.When the quantum dots are selected from core-shell structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots are respectively selected from at least one of II-VI group compounds, IV-VI group compounds, III-V group compounds and I-III-VI group compounds; the II-VI group compounds are selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeT e, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe; the IV-VI group compound is selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSe At least one of Te, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the III-V group compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, Al At least one of PSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; the I-III-VI group compound is selected from at least one of CuInS2, CuInSe2 and AgInS2.

[0050] As an example, the core-shell structured quantum dots may be selected from but not limited to at least one of CdZnSe / CdZnSe / ZnSe / CdZnS / ZnS, CdZnSe / CdZnSe / CdZnS / ZnS CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS and InP / ZnSe / ZnS.

[0051] It should be noted that, for the material of the aforementioned single structure quantum dot, or the material of the core of the core-shell structure quantum dot, or the material of the shell of the core-shell structure quantum dot, the chemical formula provided only indicates the elemental composition, but does not indicate the content of each element. For example, CdZnSe only indicates that it is composed of three elements, Cd, Zn and Se. If the content of each element is indicated, it corresponds to Cd x Zn 1-x Se,0 <x<1。

[0052] In some embodiments, the present application provides a method for preparing quantum dots, and the above-mentioned quantum dots can be prepared by the preparation method.

[0053] See also Figure 1 , the method for preparing quantum dots comprises the following steps:

[0054] S10, providing a precursor solution for synthesizing nanoparticles;

[0055] S20, providing a micro-reaction channel, wherein the micro-reaction channel comprises a first heating section and a second heating section, wherein the first heating section is heated by microwaves;

[0056] S30, injecting the precursor solution into the micro-reaction channel, the precursor solution flows through the first heating section and the second heating section in sequence to obtain nanoparticles, and the quantum dots include the nanoparticles.

[0057] Specifically, when the quantum dots to be prepared are single-structure quantum dots, please refer to Figure 2 , the method for preparing the single structure quantum dots comprises the following steps:

[0058] S10a, providing a precursor solution for synthesizing single-structure quantum dots;

[0059] S20a, providing a micro-reaction channel, wherein the micro-reaction channel comprises a first heating section and a second heating section, wherein the first heating section is heated by microwaves;

[0060] S30a, injecting the precursor solution into the micro-reaction channel, and the precursor solution flows through the first heating section and the second heating section in sequence to generate nanoparticles, that is, to obtain single-structure quantum dots.

[0061] When the quantum dots are core-shell quantum dots, please refer to Figure 3 The method for preparing the core-shell structure quantum dots comprises the following steps:

[0062] S10b, providing a precursor solution of a quantum dot core for synthesizing a core-shell structured quantum dot;

[0063] S20b, providing a micro-reaction channel, wherein the micro-reaction channel comprises a first heating section, a second heating section, a feeding section and a third heating section which are connected in sequence, wherein the first heating section is heated by microwaves;

[0064] S30b, injecting the precursor solution into the micro-reaction channel, and the precursor solution sequentially flows through the first heating section and the second heating section to generate a first liquid containing nanoparticles;

[0065] S40b, providing a shell precursor solution, injecting the shell precursor solution into the feeding section, mixing it with the first liquid output from the second heating section to form a mixed solution, and the mixed solution flows through the third heating section to form a shell on the surface of the nanoparticles to obtain core-shell structured quantum dots.

[0066] In some embodiments, the diameter of the microreaction channel is 0.39 to 50 nm. By injecting the precursor solution into the microreaction channel, the fluid reaction can be precisely controlled and its reaction volume can be controlled at the micron level, which helps to greatly improve the synthesis efficiency of the reaction. At the same time, in this microfluidic method, the precursor solution is continuously injected and flows continuously, thereby realizing continuous and large-scale synthesis of quantum dots.

[0067] In some embodiments, the material of the micro-reaction channel may be polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), quartz capillary, etc.

[0068] Since the precursor solution flows continuously in the pipeline in the micro-reaction channel, when it is heated, not only will the flow make it impossible to achieve hot injection for batch synthesis, but the heat transfer in the pipeline and the flow of the fluid will cause the temperature rise of the solution to be uneven, for example, the temperature of the fluid near the inner wall of the channel is higher than the temperature of the fluid at the center of the channel, which makes it difficult for the solutions in the same flow section to nucleate at the same time, thereby causing the uniformity of the quantum dots to decrease. The embodiment of the present application adopts microwave heating in the first heating section of the micro-reaction channel, which can heat the precursor solution in a very short time and very uniformly, so that the same section of the fluid can reach the nucleation temperature in a very short time, so that the nucleation can be precisely controlled at the same time, thereby promoting the preparation of single-structure quantum dots with uniform size, or quantum dot cores of core-shell structure quantum dots with uniform size.

[0069] In some embodiments, the second heating section may be heated by a conventional heating method, for example, the second heating section may be heated by a heating medium such as thermal oil. In the embodiment of the present application, microwave heating is used in the first heating section, and conventional heating is used in the second heating section, which can improve the uniformity of quantum dot size while reducing energy consumption and production costs.

[0070] It can be understood that different precursor solutions can be used according to the different types of final product quantum dots. For ease of description, in this article, the precursor solution used to prepare single-structure quantum dots and the precursor solution used to prepare the quantum dot core of the core-shell structure quantum dots are both referred to as the first precursor solution. In some embodiments, the first precursor solution includes a first cationic precursor solution and a first anionic precursor solution. The first cationic precursor solution and the first anionic precursor solution can be injected into the micro-reaction channel at a micro-flow rate and mixed, or they can be mixed first and then injected into the micro-reaction channel.

[0071] The first cation precursor solution includes a first cation precursor and a first solvent; the first anion precursor solution includes a first anion precursor and a second solvent. The first cation precursor includes at least one of a cadmium source, a zinc source, an indium source, a copper source, and a silver source; the first anion precursor includes at least one of a selenium source, a sulfur source, a tellurium source, and a phosphorus source; the first solvent and the second solvent are independently selected from at least one of tetradecene, pentadecene, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, octadecene, oleic acid, oleylamine, trioctylphosphine, and trioctylphosphine oxide.

[0072] It can be understood that the first cation precursor and the first anion precursor can be selected according to the type of quantum dots to be prepared. For example, when the quantum dots to be prepared are single-structure quantum dots CdSe or core-shell structure quantum dots CdSe / ZnS, the first cation precursor required is a cadmium source, and the first anion precursor is a selenium source; when the quantum dots to be prepared are single-structure quantum dots CdZnSe or core-shell structure quantum dots CdZnSe / ZnS, the first cation precursor required is a cadmium source and a zinc source, and the first anion precursor is a selenium source.

[0073] It is understood that for a precursor solution with relatively poor fluidity or poor solubility, the precursor solution may be preheated before being mixed with other precursor solutions. For example, cadmium oleate may be preheated at 40 to 60° C. at room temperature before being mixed with other precursor solutions to make it fluid.

[0074] In some embodiments, during microwave heating, the microwave power is 400-1100 W; for example, it can be 400 W, 500 W, 600 W, 800 W, 900 W, 1000 W, 1100 W, and any value between the above two values. By controlling the microwave power within this range, the fluid in the first heating section can be well heated to promote its reaction nucleation.

[0075] In some embodiments, the residence time of the first precursor solution in the first heating section is controlled to be 2 to 9 seconds; for example, it can be 2 seconds, 3 seconds, 4 seconds, 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, and values ​​between any two of the above values. For continuous fluid reactions, the residence time refers to the time that the fluid stays in a channel of a certain length, that is, the time from the fluid entering the first heating section to the fluid leaving the first heating section. By controlling the residence time within this range, the nucleation time can be accurately controlled; further, by controlling the above extremely short residence time with a microwave power of 400 to 1100 W, the fluid in the first heating section can be effectively and accurately controlled to react and nucleate effectively and fully in the shortest possible time, thereby achieving simultaneous nucleation. In actual processing, the residence time can be controlled by adjusting the length and diameter of the first heating section, the fluid flow rate, etc.

[0076] In some embodiments, the flow rate of the first precursor solution in the first heating section is 0.01 to 10 ml / min; for example, it can be 0.01 ml / min, 0.02 ml / min, 0.04 ml / min, 0.05 ml / min, 0.1 ml / min, 0.5 ml / min, 1 ml / min, 2 ml / min, 3 ml / min, 4 ml / min, 5 ml / min, 6 ml / min, 7 ml / min, 8 ml / min, 9 ml / min, 10 ml / min and values ​​between any two of the above values.

[0077] In some embodiments, the heating temperature of the second heating section is 200-290°C; for example, it can be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C and any two values ​​between the above. The heating temperature refers to the temperature reached by heating the second heating section to the internal fluid. Controlling the heating temperature of the second heating section within this range can promote the good maturation growth of the initially nucleated nanoparticles.

[0078] In some embodiments, the residence time of the first precursor solution in the second heating section is controlled to be 10 to 60 minutes; for example, it can be 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, and a value between any two of the above values.

[0079] In some embodiments, the temperature of the first heating section is greater than the temperature of the second heating section. The fluid reaches the nucleation temperature instantly in the first heating section, and a large number of nuclei are simultaneously nucleated. Then, by regulating the temperature, the nucleation frequency is suppressed, so that more precursors tend to grow on the basis of the existing nuclei to form nanoparticles. This helps to regulate the size of the generated nanoparticles, reduce size differences, and improve uniformity.

[0080] Furthermore, in some embodiments, the temperature difference between the first heating section and the second heating section is 20-40°C; for example, it can be 20°C, 22°C, 25°C, 27°C, 29°C, 30°C, 31°C, 33°C, 35°C, 36°C, 38°C, 39°C, 40°C and values ​​between any two of the above values. By controlling the temperature difference, it is helpful to better regulate the nucleation frequency and the growth frequency of nanoparticles and improve the uniformity of the nanoparticles.

[0081] After heating in the second heating section, nanoparticles can be prepared. The nanoparticles can be used as quantum dots with a single structure or as quantum dot cores of quantum dots with a core-shell structure.

[0082] Specifically, when the quantum dots to be prepared are single-structure quantum dots, the nanoparticles formed in the second heating section are single-structure quantum dots.

[0083] When the quantum dots to be prepared are core-shell structure quantum dots, the quantum dots are composed of the nanoparticles and the shells coated outside the nanoparticles, and the nanoparticles formed in the second heating section constitute the cores of the core-shell structure quantum dots. Accordingly, after the step of injecting the first precursor solution into the micro-reaction channel and the first precursor solution sequentially flowing through the first heating section and the second heating section to obtain the nanoparticles, a step of forming a shell layer on the surface of the nanoparticles is also included. Specifically, steps S30b and S40b: the micro-reaction channel also includes a feeding section and a third heating section that are connected in sequence, wherein the inlet of the feeding section is connected to the outlet of the second heating section, and after the fluid flows out from the outlet of the second heating section, it is mixed with the new material solution added in the feeding section to form a mixed solution, and the mixed solution enters the third heating section to undergo a shell-forming reaction to form a shell, thereby obtaining quantum dots with a core-shell structure.

[0084] In some embodiments, the shell precursor solution includes a shell cation precursor solution and a shell anion precursor solution. The shell cation precursor solution and the shell anion precursor solution can be respectively injected into the feeding section at a micro flow rate for mixing, or mixed first and then injected into the feeding section.

[0085] The shell cation precursor solution includes a shell cation precursor and a third solvent; the shell anion precursor solution includes a shell anion precursor and a fourth solvent. The shell cation precursor includes at least one of a cadmium source, a zinc source, an indium source, a copper source, and a silver source; the shell anion precursor includes at least one of a selenium source, a sulfur source, a tellurium source, and a phosphorus source; the third solvent and the fourth solvent are each independently selected from at least one of tetradecene, pentadecene, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, octadecene, oleic acid, oleylamine, trioctylphosphine, and trioctylphosphine oxide.

[0086] It can be understood that the shell cation precursor and the shell anion precursor can be selected according to the type of quantum dot shell to be prepared. For example, when the quantum dot shell to be prepared is ZnSe, the required shell cation precursor is a zinc source and the shell anion precursor is a selenium source; when the quantum dot shell to be prepared is ZnS, the required cationic precursor is a zinc source and the shell anion precursor is a sulfur source.

[0087] In some embodiments, the heating temperature of the third heating section is 250-320°C; for example, it can be 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C and values ​​between any two of the above values.

[0088] In some embodiments, the residence time of the mixed solution in the third heating section is controlled to be 10 to 60 minutes; for example, it can be 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, and a value between any two of the above values.

[0089] In addition, the present application also proposes a quantum dot synthesis system. Figure 5 As shown. The synthesis system of quantum dots includes a microfluidic reaction device and a microwave heating device (not shown), the microfluidic reaction device includes a micro reaction channel, the micro reaction channel has a plurality of channel segments, the plurality of channel segments include a first heating segment 301 and a second heating segment 302 sequentially arranged along the material conveying direction, and the microwave heating device is arranged corresponding to the first heating segment 301, and is used to heat the first heating segment 301. The synthesis system of this embodiment is used to prepare quantum dots, with high production efficiency and low cost, and the prepared quantum dots have high uniformity.

[0090] In some embodiments, the synthesis system further includes a first heater (not shown), which is disposed corresponding to the second heating section 302 and is used to heat the second heating section 302. The first heater 301 may be a heater commonly used in microfluidic devices, such as a heating wire or a heat transfer medium such as heat transfer oil.

[0091] In some embodiments, the plurality of channel sections further include a feeding section 303 and a third heating section 304 that are connected in sequence, wherein the inlet of the feeding section 303 is connected to the outlet of the second heating section 302, and the outlet of the feeding section 303 is connected to the third heating section 304. The feeding section 303 is used to add new reaction raw materials after the reaction in the second heating section is completed.

[0092] In some embodiments, the microfluidic reaction device further comprises a plurality of injection pipes, and the outlets of the plurality of injection pipes are all connected to the inlet of the micro-reaction channel. A variety of raw material solutions participating in the reaction can be injected from the plurality of injection pipes respectively and mixed in the micro-reaction channel. In some embodiments, the synthesis system further comprises a plurality of injection pumps, and the plurality of injection pumps are connected to the plurality of injection pipes in a one-to-one correspondence.

[0093] In some embodiments, the synthesis system also includes a second heater (not shown), which is arranged corresponding to the third heating segment 304 and is used to heat the third heating segment 304; the second heater 302 can be a heater commonly used in microfluidic devices, for example, it can be a heating wire, or it can be a heat transfer medium such as heat transfer oil.

[0094] In some embodiments, the feeding section 303 has a feeding port. The microfluidic reaction device further comprises at least one feeding pipeline, and the outlet of the at least one feeding pipeline is connected to the feeding port of the feeding section 303. In some embodiments, the synthesis system further comprises a feeding pump 2, and the feeding pump 2 is connected to the feeding pipeline.

[0095] In a specific embodiment, if Figure 5 The synthesis system shown in the figure comprises three injection pumps 1, a feeding pump 2, a microwave heating device, a first heater, a second heater and a micro-reaction channel. The outlets of the three injection pumps 1 are all connected to the inlet of the micro-reaction channel; the micro-reaction channel has a first heating section 301, a second heating section 302, a feeding section 303 and a third heating section 304, the microwave heating device is arranged corresponding to the first heating section 301, the first heater is arranged corresponding to the second heating section 302, the feeding pump 2 is connected to the feeding section 303, and the second heater is arranged corresponding to the third heating section 304.

[0096] In addition, the present application also proposes a light emitting device 100, which may be a quantum dot light emitting diode (QLED). Figure 4 The light emitting device 100 includes a first electrode, a light emitting layer 20 and a second electrode. The material of the light emitting layer 20 includes the quantum dots described above. The quantum dots have good uniformity, and the light emitting layer 20 made of the quantum dots has a good film-forming effect, which helps to improve the light emitting performance and life of the light emitting device 100.

[0097] The first electrode may be one of the anode 10 and the cathode 40 , and the second electrode may be the other of the anode 10 and the cathode 40 . In some embodiments, the anode 10 can be an anode 10 for a light-emitting device 100 known in the art, for example, can be selected from but not limited to a doped metal oxide particle electrode, a composite electrode of a metal and a metal oxide, a graphene electrode, a carbon nanotube electrode, a metal electrode or an alloy electrode, the material of the doped metal oxide particle electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide, the composite electrode of a metal and a metal oxide is selected from 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, the material of the metal electrode is selected from one or more of Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg and Ba.

[0098] The cathode 40 can be a cathode 40 for the light-emitting device 100 known in the art, for example, can be selected from but not limited to a doped metal oxide particle electrode, a composite electrode of metal and metal oxide, a graphene electrode, a carbon nanotube electrode, a metal electrode or an alloy electrode, the material of the doped metal oxide particle electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide, the composite electrode of metal and metal oxide is selected from 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, and the material of the metal electrode is selected from one or more of Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg and Ba.

[0099] In some embodiments, the light-emitting device 100 further includes a hole transport layer 50, and the hole transport layer 50 is disposed between the light-emitting layer 20 and the anode 10. The material of the hole transport layer 50 includes 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), 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), N,N'-bis(3-methylphenyl)-N,N'-bis(1,1'-biphenyl)-4,4'-diamine (TPD), (phenyl)-spiro (spiro-TPD), N,N'-di(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine (DNTPD), tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA), poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))] (TFB), and poly(4-butylphenyl-diphenylamine) One or more of poly(vinylamine) (poly-TPD), polyaniline, polypyrrole, poly(p-phenylene vinylene) (PPV), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MOMO-PPV), copper phthalocyanine, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, poly(N-vinylcarbazole) (PVK) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-di(naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB), and spiro NPB.

[0100] In some embodiments, the light emitting device 100 further includes a hole injection layer 60, and the hole injection layer 60 is disposed between the hole transport layer 50 and the anode 10. The material of the hole injection layer 60 may include, but is not limited to, poly(ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine, poly(N-vinylcarbazole), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), 4,4',4"-tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA), 4,4',4 ”-tri(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-tolylamino)phenylcyclohexane (TAPC), 4,4',4"-tri(diphenylamino)triphenylamine (TDATA) doped with tetrafluoro-tetracyano-quinodimethane (F4-TCNQ), p-doped phthalocyanine (e.g., F4-TCNQ-doped zinc phthalocyanine (ZnPc)), F4-TCNQ-doped N,N'-diphenyl-N,N'-di(1-naphthyl)-1,1'-biphenyl-4,4"-diamine (α-NPD), hexaazatriphenylene-capronitrile (HAT-CN) or one or more thereof.

[0101] In some embodiments, the light-emitting device 100 also includes an electron transport layer 30 arranged between the light-emitting layer 20 and the cathode 40. The material of the electron transport layer 30 can be a material known in the art for the light-emitting device 100 and having electron transport properties, for example, it can include but is not limited to one or more of metal oxides and doped metal oxides; the metal oxide includes one or more of ZnO, TiO2, SnO2, ZrO, Al2O3, WO3, HfO3, Ta2O3, ZrSiO4, BaTiO3, and BaZrO3; the metal oxide in the doped metal oxide includes a variety of ZnO, TiO2, SnO2, ZrO, Al2O3, WO3, HfO3, Ta2O3, ZrSiO4, BaTiO3, and BaZrO3, and the doping elements include one or more of Al, Mg, Li, In, Ga, Cd, Cs, and Cu.

[0102] It can be understood that the light emitting device 100 can be an upright device or an inverted device.

[0103] It is understandable that the light emitting device 100 may also be further provided with some functional layers conventionally used in the light emitting device 100 to help improve the performance of the light emitting device 100, such as an electron injection layer, an electron blocking layer, an interface modification layer, etc.

[0104] It can be understood that the material and thickness of each layer of the light emitting device 100 can be adjusted according to the actual requirements of the light emitting device 100 .

[0105] Based on the above-mentioned embodiment of the light-emitting device 100 , a method for preparing the light-emitting device 100 is further proposed. The method comprises: preparing a plurality of film layers in sequence according to a preset order of the plurality of film layers to obtain the light-emitting device 100 .

[0106] The plurality of film layers include an anode 10, a cathode 40, a light-emitting layer 20, a hole transport layer 50, a hole injection layer 60, and an electron transport layer 30. The preset order of the plurality of film layers can be adjusted according to the device type. For example, the film layer order of the upright device is the anode 10, the hole injection layer 60, the hole transport layer 50, the light-emitting layer 20, the electron transport layer 30, and the cathode 40 stacked in sequence from bottom to top; accordingly, in actual preparation, the anode 10, the hole injection layer 60, the hole transport layer 50, the light-emitting layer 20, the electron transport layer 30, and the cathode 40 are prepared in sequence. The film layer order of the inverted device is opposite to that of the upright device. Accordingly, in actual preparation, the cathode 40, the electron transport layer 30, the light-emitting layer 20, the hole transport layer 50, the hole injection layer 60, and the anode 10 are prepared in sequence.

[0107] In some embodiments, each film layer can be realized by conventional techniques in the art, such as chemical methods or physical methods. Among them, chemical methods include chemical vapor deposition, continuous ion layer adsorption and reaction, anodization, electrolytic deposition, and coprecipitation. Physical methods include physical coating and solution methods, among which physical coating includes: thermal evaporation coating, electron beam evaporation coating, magnetron sputtering, multi-arc ion coating, physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc.; solution methods can be spin coating, printing, inkjet printing, doctor blade coating, printing, dip-coating, immersion, spraying, roller coating, casting, slit coating, and strip coating, etc.

[0108] The technical scheme and technical effects of the present application are described in detail below through specific embodiments and comparative examples. The following embodiments are only some embodiments of the present application and do not specifically limit the present application.

[0109] Example 1

[0110] (1) First precursor solution: Cadmium oleate is dispersed in octadecene to prepare a cadmium precursor solution with a concentration of 0.2 mol / L; selenium powder is dispersed in trioctylphosphine to prepare a selenium precursor solution with a concentration of 0.18 mol / L.

[0111] Shell precursor solution: Disperse zinc oleate in octadecene to obtain a zinc precursor solution with a concentration of 0.3 mol / L; disperse sulfur powder in trioctylphosphine to obtain a sulfur precursor solution with a concentration of 0.2 mol / L. Mix the zinc precursor solution and the sulfur precursor solution to obtain a shell precursor solution.

[0112] (2) Providing a micro-reaction channel, the micro-reaction channel having a first heating section, a second heating section, a feeding section and a third heating section; wherein the first heating section is in a microwave environment, and the second heating section and the third heating section are in a thermal environment where heating is provided by an electric heating wire.

[0113] (3) The cadmium precursor solution and the selenium precursor solution are respectively injected into a micro-reaction channel (with a tube diameter of 1 mm) for mixing to form a first precursor solution; the shell precursor solution is injected into the feeding section and mixed with the solution flowing out of the second heating section to form a mixed solution.

[0114] The first heating section is heated by microwave, the microwave power is 800W (the temperature of the fluid in the first heating section is about 320°C), the flow rate of the precursor solution is controlled to be 1ml / min, so that the time t1 from the solution flowing into the first heating section to flowing out of the first heating section is 5s; at the same time, the liquid entering the second heating section is heated, the temperature T1 of this section is controlled to be 280°C (that is, the temperature difference between the first heating section and the second heating section is 40°C), and the time t2 of the solution flowing into the second heating section to flowing out of the second heating section is 30min; the mixed solution entering the third heating section is heated, the temperature T2 of this section is controlled to be 230°C, and the time t3 of the solution flowing into the third heating section to flowing out of the third heating section is 30min. The liquid flowing out of the third heating section is precipitated and solid-liquid separated to obtain quantum dots CdSe / ZnS.

[0115] (4) The quantum dots were redispersed in n-hexane to obtain a 30 mg / mL quantum dot solution.

[0116] Example 2

[0117] The scheme of this embodiment is basically the same as that of embodiment 1, with the only difference being that in this embodiment, in step (3), the microwave power is changed to 400 W (the fluid temperature in the first heating section is about 260° C.), T1 is changed to 220° C., and accordingly, the temperature difference between the first heating section and the second heating section is 40° C.

[0118] Example 3

[0119] The scheme of this embodiment is basically the same as that of Embodiment 1, with the only difference being that in this embodiment, in step (3), the microwave power is changed to 1100 W (the fluid temperature in the first heating section is about 335° C.), T1 is changed to 295° C., and accordingly, the temperature difference between the first heating section and the second heating section is 40° C.

[0120] Example 4

[0121] The scheme of this embodiment is basically the same as that of embodiment 1, with the only difference being that in this embodiment, in step (3), the microwave power is changed to 300 W (the fluid temperature in the first heating section is about 250° C.), T1 is changed to 210° C., and accordingly, the temperature difference between the first heating section and the second heating section is 40° C.

[0122] Example 5

[0123] The scheme of this embodiment is basically the same as that of embodiment 1, with the only difference being that in this embodiment, in step (3), the microwave power is changed to 1200 W (the fluid temperature in the first heating section is about 340° C.), T1 is changed to 295° C., and accordingly, the temperature difference between the first heating section and the second heating section is 45° C.

[0124] Example 6

[0125] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t1 is changed to 2s.

[0126] Example 7

[0127] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t1 is changed to 9s.

[0128] Example 8

[0129] The scheme of this embodiment is basically the same as that of embodiment 1, except that in this embodiment, in step (3), t1 is changed to 1s.

[0130] Example 9

[0131] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t1 is changed to 10s.

[0132] Example 10

[0133] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, the quantum dots are CdSe; accordingly:

[0134] In step (3), the steps of "taking the shell precursor solution and injecting it into the feeding section to mix it with the solution flowing out of the second heating section to form a mixed solution" and "heating the mixed solution entering the third heating section, controlling the temperature T2 of this section to 230°C, and the time t3 from the solution flowing into the third heating section to flowing out of the third heating section to 30 minutes" are omitted, and the liquid flowing out of the second heating section is directly precipitated and solid-liquid separated. The obtained product is quantum dot CdSe, which is used in step (4).

[0135] Embodiment 11

[0136] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, the quantum dots are CdZnSe / ZnS; correspondingly:

[0137] In step (1), the first precursor solution is changed to: dispersing cadmium oleate in octadecene to obtain a cadmium precursor solution with a concentration of 0.1 mol / L; dispersing selenium powder in trioctylphosphine to obtain a selenium precursor solution with a concentration of 0.18 mol / L; dispersing zinc oleate in octadecene to obtain a zinc precursor solution with a concentration of 0.1 mol / L;

[0138] In step (3), the sentence “the cadmium precursor solution and the selenium precursor solution are respectively injected into a micro-reaction channel (with a tube diameter of 1 mm) for mixing to form a first precursor solution” is changed to “the cadmium precursor solution, the zinc precursor solution and the selenium precursor solution are respectively injected into a micro-reaction channel (with a tube diameter of 1 mm) for mixing to form a first precursor solution”.

[0139] Example 12

[0140] The scheme of this embodiment is basically the same as that of embodiment 2, except that, in this embodiment, in step (3), T1 is changed to 200° C., and accordingly, the temperature difference between the first heating section and the second heating section is 60° C.

[0141] Embodiment 13

[0142] The scheme of this embodiment is basically the same as that of embodiment 2, except that in this embodiment, in step (3), T1 is changed to 230°C, and accordingly, the temperature difference between the first heating section and the second heating section is 30°C.

[0143] Embodiment 14

[0144] The scheme of this embodiment is basically the same as that of embodiment 2, except that, in this embodiment, in step (3), T1 is changed to 240°C, and accordingly, the temperature difference between the first heating section and the second heating section is 20°C.

[0145] Embodiment 15

[0146] The scheme of this embodiment is basically the same as that of embodiment 2, except that, in this embodiment, in step (3), T1 is changed to 250° C., and accordingly, the temperature difference between the first heating section and the second heating section is 10° C.

[0147] Example 16

[0148] The scheme of this embodiment is basically the same as that of embodiment 2, except that, in this embodiment, in step (3), T1 is changed to 190° C., and accordingly, the temperature difference between the first heating section and the second heating section is 70° C.

[0149] Embodiment 17

[0150] The scheme of this embodiment is basically the same as that of embodiment 1, except that in this embodiment, in step (3), T2 is 250°C.

[0151] Embodiment 18

[0152] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), T2 is 330°C.

[0153] Embodiment 19

[0154] The scheme of this embodiment is basically the same as that of embodiment 1, except that in this embodiment, in step (3), T2 is 240°C.

[0155] Embodiment 20

[0156] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t2 is 10 min.

[0157] Embodiment 21

[0158] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t2 is 60 min.

[0159] Embodiment 22

[0160] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t2 is 5 min.

[0161] Embodiment 23

[0162] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t2 is 80 min.

[0163] Embodiment 24

[0164] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t3 is 10 min.

[0165] Embodiment 25

[0166] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t3 is 60 min.

[0167] Embodiment 26

[0168] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t3 is 5 min.

[0169] Embodiment 27

[0170] The scheme of this embodiment is basically the same as that of embodiment 1, except that, in this embodiment, in step (3), t3 is 80 min.

[0171] Embodiment 28

[0172] The scheme of this embodiment is basically the same as that of embodiment 10, with the only difference being that, in this embodiment, in step (3), t1 is changed to 2s.

[0173] Embodiment 29

[0174] The scheme of this embodiment is basically the same as that of embodiment 10, with the only difference being that, in this embodiment, in step (3), t1 is changed to 9s.

[0175] Embodiment 30

[0176] The scheme of this embodiment is basically the same as that of embodiment 10, with the only difference being that, in this embodiment, in step (3), t1 is changed to 10s.

[0177] Embodiment 31

[0178] The scheme of this embodiment is basically the same as that of embodiment 10, except that in this embodiment, the synthesized quantum dots are CdS, and accordingly, in step (3), the selenium precursor solution is replaced with the sulfur precursor solution prepared in embodiment 1.

[0179] Comparative Example 1

[0180] The comparative example is basically the same as Example 1, with the only difference being that, in the comparative example, a heater is used to heat the first heating section. Accordingly, in step (3), "heating the first heating section with microwaves at a microwave power of 800 W" is changed to "heating the first heating section with a heater until the temperature of the liquid in the section reaches 300°C".

[0181] Comparative Example 2

[0182] The comparative example is basically the same as Example 1, with the only difference being that, in this comparative example, the second heating section is not heated. Accordingly, in step (3): the step "simultaneously, the liquid entering the second heating section is heated, and the temperature T1 of the section is controlled to be 280°C, and the time t2 from the solution flowing into the second heating section to the solution flowing out of the second heating section is 30 minutes" is omitted.

[0183] Comparative Example 3

[0184] The comparative example is basically the same as Example 10, with the only difference being that, in the comparative example, a heater is used to heat the first heating section. Accordingly, in step (3), "heating the first heating section with microwaves at a microwave power of 800 W" is changed to "heating the first heating section with a heater until the temperature of the liquid in the section reaches 300°C".

[0185] Comparative Example 4

[0186] The comparative example is basically the same as Example 11, with the only difference being that, in the comparative example, a heater is used to heat the first heating section. Accordingly, in step (3), "heating the first heating section with microwaves at a microwave power of 800 W" is changed to "heating the first heating section with a heater until the temperature of the liquid in the section reaches 300°C".

[0187] The quantum dots prepared in the above embodiments and comparative examples were tested using a transmission electron microscope (TEM) and an Edinburgh spectrometer. The results are recorded in Table 1.

[0188] Table 1

[0189]

[0190]

[0191]

[0192] Refer to Table 1, we can see that:

[0193] Examples 1 to 9 and Examples 12 to 27 have smaller TEM particle size differences than Comparative Examples 1 to 2, Examples 10 and 28 to 31 have smaller TEM particle size differences than Comparative Example 3, and Example 11 has smaller TEM particle size differences than Comparative Example 4. At the same time, each example has a high PLQY, indicating that preparing quantum dots by microfluidic method, using microwave heating in the first heating stage, and then constant temperature aging can effectively improve the size uniformity while preparing high PLQY quantum dots.

[0194] The quantum dots, preparation methods, synthesis systems and light-emitting devices provided in the embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the methods and core ideas of the present application. At the same time, for technicians in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing quantum dots, characterized in that: The following steps are involved: Providing a precursor solution for synthesizing nanoparticles; Providing a micro-reaction channel, the micro-reaction channel comprising a first heating section and a second heating section; Injecting the precursor solution into the micro-reaction channel, the precursor solution sequentially flows through the first heating section and the second heating section to obtain nanoparticles, wherein the quantum dots include the nanoparticles; Wherein, the first heating section adopts microwave heating.

2. The preparation method according to claim 1, characterized in that: During the microwave heating, the microwave power is 400-1100W; and / or, The residence time of the precursor solution in the first heating section is controlled to be 2 to 9 seconds.

3. The preparation method according to claim 1, characterized in that: The flow rate of the precursor solution in the first heating section is 0.01-10 ml / min.

4. The preparation method according to claim 1, characterized in that: The heating temperature of the second heating section is 200-290° C.; and / or, The residence time of the precursor solution in the second heating section is controlled to be 10 to 60 minutes; and / or the temperature of the first heating section is greater than the temperature of the second heating section.

5. The preparation method according to claim 4, characterized in that: The temperature difference between the first heating section and the second heating section is 20-40°C.

6. The preparation method according to claim 1, characterized in that: The quantum dots include one of single structure quantum dots and core-shell structure quantum dots; When the quantum dot is a single-structure quantum dot, the nanoparticles constitute the quantum dot; When the quantum dots are core-shell structured quantum dots, the quantum dots are composed of the nanoparticles and a shell covering the nanoparticles.

7. The preparation method according to claim 6, characterized in that: The micro-reaction channel further comprises a feeding section and a third heating section which are connected in sequence, wherein the inlet of the feeding section is connected to the outlet of the second heating section; When the quantum dots are core-shell structure quantum dots, after the step of injecting the precursor solution into the micro-reaction channel and the precursor solution sequentially flowing through the first heating section and the second heating section to obtain nanoparticles, the step further includes: providing a shell precursor solution; The shell precursor solution is injected into the feeding section and mixed with the liquid output from the second heating section to form a mixed solution. The mixed solution flows through the third heating section to form a shell on the surface of the nanoparticles to obtain core-shell structured quantum dots.

8. A quantum dot, characterized in that: The invention comprises quantum dots prepared by the preparation method according to any one of claims 1 to 7.

9. The quantum dot according to claim 8, characterized in that The quantum dots include one of single structure quantum dots and core-shell structure quantum dots; the material of the single structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots are independently selected from at least one of II-VI group compounds, IV-VI group compounds, III-V group compounds and I-III-VI group compounds; the II-VI group compounds are selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnS At least one of CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe; the IV-VI group compound is selected from SnS, SnSe, SnTe, PbS, PbSe, P bTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; the III-V group compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, A At least one of lPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; the I-III-VI group compound is selected from at least one of CuInS2, CuInSe2 and AgInS2.

10. A light emitting device, characterized in that: It comprises a light-emitting layer, wherein the material of the light-emitting layer comprises quantum dots prepared by the preparation method according to any one of claims 1 to 7, or the quantum dots according to claim 8 or 9.

11. A quantum dot synthesis system, characterized in that: The invention comprises a microfluidic reaction device and a microwave heating device. The microfluidic reaction device comprises a microreaction channel. The microreaction channel has a plurality of channel sections. The plurality of channel sections comprise a first heating section and a second heating section which are sequentially arranged along a material conveying direction. The microwave heater is arranged corresponding to the first heating section and is used for heating the first heating section.

12. The synthesis system according to claim 11, characterized in that: The plurality of channel sections further include a feeding section and a third heating section which are connected in sequence, wherein an inlet of the feeding section is connected to an outlet of the second heating section; and / or, The synthesis system further comprises a first heater, which is arranged corresponding to the second heating section and is used to heat the second heating section; and / or, The microfluidic reaction device further comprises a plurality of injection pipes, and the outlets of the plurality of injection pipes are all connected to the inlet of the micro reaction channel.

13. The synthesis system according to claim 11, characterized in that: The synthesis system further comprises a second heater, which is arranged corresponding to the third heating section and is used to heat the third heating section; and / or, The feeding section has a feeding port; the microfluidic reaction device also includes at least one feeding pipeline, and the outlet of the at least one feeding pipeline is connected to the feeding port of the feeding section.

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