CN111019656A - Preparation method of quantum dots - Google Patents
Preparation method of quantum dots Download PDFInfo
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Abstract
The invention provides a preparation method of quantum dots, which comprises the following steps: providing an initial quantum dot core, mixing the initial quantum dot core with an organic carboxylic acid, and bonding the organic carboxylic acid to the surface of the initial quantum dot core; preparing a shell layer on the surface of the initial quantum dot core, wherein the step of preparing the shell layer on the surface of the initial quantum dot core is carried out in a shell layer growth reaction system containing organic carboxylic acid; mixing the solution system after the growth reaction of the shell layer is finished with organic amine to complex the organic amine and the rest of the cation precursor shell; or mixing the system after the growth reaction of the shell layer is finished with the organic phosphine and heating; or mixing the solution system after the shell growth reaction is finished with the mixed solution of organic amine and organic phosphine, and heating.
Description
Technical Field
The invention belongs to the technical field of nanocrystalline material preparation, and particularly relates to a preparation method of quantum dots.
Background
Nanoscience and nanotechnology are emerging scientific technologies and have potential application value and economic benefits, and thus are receiving attention of scientists worldwide. Nanocrystals (NCs) can exhibit electrical, optical, magnetic, and electrochemical properties that bulk materials do not possess relative to bulk materials. Semiconductor nanocrystals, also known as Quantum Dots (QDs), range in size from 1 to 20nm, and when the size of the particle size is varied, the band gap valence band and conduction band of the semiconductor nanocrystal are also altered (quantum size effect), such as absorption and emission of CdSe nanocrystals covering almost the entire visible spectral range, and thus, semiconductor nanocrystals exhibit size-dependent phenomena of photoluminescence. Semiconductor nanocrystals have been used in many areas of technology such as biomarkers, diagnostics, chemical sensors, light emitting diodes, electroluminescent devices, photovoltaic devices, lasers, and electronic transistors, among others. However, different types of semiconductor quantum dots are required to be prepared aiming at the application in different technical fields, and the preparation of high-quality semiconductor quantum dots is a precondition for the effective application of the size effect of the semiconductor quantum dots.
In the past decades, researchers have developed a number of methods to obtain high quality semiconductor nanocrystals. The prior art mainly comprises surface ligand modification and core-shell structure design. In the design of the core-shell structure, the core is made of a narrow-bandgap semiconductor material, and the shell is made of a wide-bandgap material. The synthesis means of the core-shell structure mainly comprises a one-step method, a two-step method and a three-step method. The one-step method refers to that the core-shell quantum dots are subjected to long core and long shell in one reaction vessel. The two-step method means that the preparation of the core-shell quantum dot comprises two steps: and (3) carrying out core growing in a reaction vessel, taking out the quantum dot core, and placing the quantum dot core in another reaction solvent for shell growing. The three-step method refers to that the preparation of the core-shell quantum dot comprises two steps: and one reaction vessel is used for carrying out core growth, the quantum dot cores are taken out and then placed in another reaction solvent for intermediate shell layer growth, and the core-shell quantum dots containing the intermediate shell layers are taken out and placed in a third reaction vessel for outermost shell layer growth. At present, a shell layer growth mode adopted for preparing the quantum dots with the core-shell structure is utilized, whether the shell layer is a one-step long shell, a two-step long shell or a three-step long shell, the shell source precursor is generally used for continuous injection growth, and the method can not well control the shell layer growth quality, so that the obtained quantum dots with the core-shell structure have fewer surface ligands and poor dissolubility. Therefore, the research on the growth mode of the shell layer of the core-shell quantum dot and the control of the growth of the shell layer are of great significance.
Disclosure of Invention
The invention aims to provide a preparation method of a core-shell structure nanocrystal, and aims to solve the problems that in the prior art, a core-shell structure quantum dot prepared by a shell source precursor in a continuous injection growth mode has fewer surface ligands and poor solubility.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a preparation method of a quantum dot with a core-shell structure, which comprises the following steps:
providing an initial quantum dot core, mixing the initial quantum dot core with an organic carboxylic acid, and bonding the organic carboxylic acid to the surface of the initial quantum dot core;
preparing a shell layer on the surface of the initial quantum dot core, wherein the step of preparing the shell layer on the surface of the initial quantum dot core is carried out in a shell layer growth reaction system containing organic carboxylic acid;
mixing and heating the solution system after the shell growth reaction is finished with organic amine, and/or mixing and heating the system after the shell growth reaction is finished with organic phosphine; or
And mixing the solution system after the shell growth reaction is finished with the mixed solution of organic amine and organic phosphine, and heating.
According to the preparation method of the quantum dot, the initial quantum dot core is mixed with the organic carboxylic acid, and the organic carboxylic acid tends to be combined with the cationic surface of the initial quantum dot core, so that the organic carboxylic acid is combined with the surface of the initial quantum dot core and is used for filling the cationic vacancy of the quantum dot core, reducing the defect state between core-shell interfaces and providing a good epitaxial interface for the growth of a shell layer. Meanwhile, the organic carboxylic acid can also play a role in passivating the surface of the quantum dot core, so that the quantum dot core cannot be self-cured in the stage of heating to the long shell temperature, and the quantum dot with uniform particle size is obtained. In the subsequent long shell process, the organic ligand after pyrolysis of the shell source anion precursor and the shell source cation precursor and the organic carboxylic acid in the shell layer growth reaction system are jointly combined and bound on the surface of the shell layer, so that the prepared core-shell structure quantum dot has good monodispersity.
After the growth of the shell layer is finished, continuously mixing the system after the growth reaction of the shell layer with at least one of organic phosphine and/or organic amine for subsequent treatment, wherein when the system after the growth reaction of the shell layer is finished is mixed with the organic phosphine for subsequent treatment, the organic phosphine is combined with the non-metallic elements on the surface of the shell layer of the nanocrystalline, so that the anion vacancy is passivated, the defect state of the surface of the core-shell nanocrystalline is reduced, and the fluorescence intensity of the quantum dot of the core-shell structure is further improved; when the system after the growth reaction of the shell layer is finished is mixed with organic amine for subsequent treatment, the organic amine can be complexed with the residual cation precursor in the mixed solution of the quantum dots with the core-shell structure, so that the freezing point of the cation precursor is reduced, the subsequent cleaning and purity of the quantum dots are facilitated, the influence of residual cation precursor impurities in the solution of the quantum dots with the core-shell structure on the stability of the device can be effectively avoided when the prepared quantum dots are used for manufacturing a device film layer, and the film forming quality of the quantum dot solid film is improved.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
The embodiment of the invention provides a preparation method of a quantum dot with a core-shell structure, which comprises the following steps:
s01, providing an initial quantum dot core, and mixing the initial quantum dot core with organic carboxylic acid to enable the organic carboxylic acid to be combined on the surface of the initial quantum dot core;
s02, preparing a shell layer on the surface of the initial quantum dot core, wherein the step of preparing the shell layer on the surface of the initial quantum dot core is carried out in a shell layer growth reaction system containing organic carboxylic acid;
s03, mixing and heating a solution system after the growth reaction of the shell layer is finished with organic amine;
or mixing the system after the growth reaction of the shell layer is finished with the organic phosphine and heating;
or mixing the solution system after the shell growth reaction is finished with the mixed solution of organic amine and organic phosphine, and heating.
According to the preparation method of the quantum dot, the initial quantum dot core is mixed with the organic carboxylic acid, and the organic carboxylic acid tends to be combined with the cationic surface of the initial quantum dot core, so that the organic carboxylic acid is combined with the surface of the initial quantum dot core, so that the cationic vacancy of the quantum dot core is filled, the defect state between core-shell interfaces is reduced, and a good epitaxial interface is provided for the growth of a shell layer. Meanwhile, the organic carboxylic acid can also play a role in passivating the surface of the quantum dot core, so that the quantum dot core cannot be self-cured in the stage of heating to the long shell temperature, and the quantum dot with uniform particle size is obtained. In the subsequent long shell process, the organic ligand after pyrolysis of the shell source anion precursor and the shell source cation precursor and the organic carboxylic acid in the shell layer growth reaction system are jointly combined and bound on the surface of the shell layer, so that the prepared core-shell structure quantum dot has good monodispersity.
After the growth of the shell layer is finished, continuously mixing the system after the growth reaction of the shell layer with at least one of organic phosphine and/or organic amine for subsequent treatment, wherein when the system after the growth reaction of the shell layer is finished is mixed with the organic phosphine for subsequent treatment, the organic phosphine is combined with the non-metallic elements on the surface of the shell layer of the nanocrystalline, so that the anion vacancy is passivated, the defect state of the surface of the core-shell nanocrystalline is reduced, and the fluorescence intensity of the quantum dot of the core-shell structure is further improved; when the system after the growth reaction of the shell layer is finished is mixed with organic amine for subsequent treatment, the organic amine can be complexed with the residual cation precursor in the mixed solution of the quantum dots with the core-shell structure, so that the freezing point of the cation precursor is reduced, the subsequent cleaning and purity of the quantum dots are facilitated, the influence of residual cation precursor impurities in the solution of the quantum dots with the core-shell structure on the stability of the device can be effectively avoided when the prepared quantum dots are used for manufacturing a device film layer, and the film forming quality of the quantum dot solid film is improved.
Specifically, in an embodiment of the step S01, the initial quantum dot core may be at least one selected from the group consisting of a group II/VI quantum dot core, a group III/V quantum dot core, a group III/VI quantum dot core, and a group II/III/VI quantum dot core, but is not limited thereto. By way of example, the group II/VI quantum dot core may be selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, CdZnSe, CdSSe, ZnSe, ZnCdS, ZnCdSe, zneses, ZnCdTe, ZnCdSSe, ZnCdSeS, and ZnCdTeS, but is not limited thereto; the group III/V quantum dot core may be selected from InAs, InP, GaAs, GaP, GaSb, InSb, AlAs, AlP, AlSb, InGaAs, GaAsP, and InAsP, but is not limited thereto; by way of example, the group III/VI quantum dot core is selected from InS, In2S3、InSe、In2Se3、In4Se3、In2Se3、InTe、In2Se3、GaS、Ga2Se3、GaSe、Ga2Se3、GaTe、Ga2Te3But are not limited thereto; the group II/III/VI quantum dot core is selected from the group consisting of CuInS, CuInZnS and CuInSeS, but is not limited thereto. Preferably, the initial quantum dot core may be selected from group II/VI quantum dot cores.
In the embodiment of the invention, the initial quantum dot core is preferably an initial quantum dot core containing a surface ligand. The surface ligand is selected from at least one of organic carboxylic acid ligand, organic phosphonic acid ligand, organic phosphine ligand and phosphine oxide ligand. Specifically, the organic carboxylic acid ligand is preferably selected from at least one of oleic acid, myristic acid and lauric acid; the organic phosphonic acid ligand is preferably selected from at least one of octadecyl phosphonic acid, tetradecyl phosphonic acid and dodecyl; the organophosphine ligand is preferably selected from at least one of, but not limited to, trioctylphosphine and tributylphosphine; the phosphine oxide ligand is preferably selected from at least one of trioctylphosphine oxide and tributylphosphine oxide.
In the step S01, the initial quantum dot core is mixed with an organic carboxylic acid, and the organic carboxylic acid tends to bind to the cationic surface of the initial quantum dot core, so that the organic carboxylic acid is bound to the surface of the initial quantum dot core, and is used to fill the cationic vacancy of the quantum dot core, reduce the defect state between the core-shell interfaces, and provide a good epitaxial interface for the growth of the shell layer. Meanwhile, the organic carboxylic acid can also play a role in passivating the surface of the quantum dot core, so that the quantum dot core cannot be self-cured in the stage of heating to the long shell temperature, and the quantum dot with uniform particle size is obtained. In the subsequent long shell process, the organic ligand after pyrolysis of the shell source anion precursor and the shell source cation precursor and the organic carboxylic acid in the shell layer growth reaction system are jointly combined and bound on the surface of the shell layer, so that the prepared core-shell structure quantum dot has good monodispersity.
Preferably, the organic carboxylic acid is selected from organic carboxylic acids with 8 to 18 carbon atoms, and in this case, relatively small steric hindrance is provided, so that the organic carboxylic acid is favorably combined to the surface of the initial quantum dot core. Further, the organic carboxylic acid is selected from linear organic carboxylic acids containing single carboxyl, and the linear organic carboxylic acids are favorable for reducing steric hindrance and promoting passivation. Specifically, the organic carboxylic acid may be at least one selected from oleic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid.
In step S01, it is preferable that in the step of mixing the initial quantum dot core with the organic carboxylic acid to facilitate sufficiently stable binding of the organic carboxylic acid to the surface of the initial quantum dot core, the mixing conditions are as follows: mixing the initial quantum dot core with organic carboxylic acid, and heating at 80-150 deg.C for 20-60min to bond the organic carboxylic acid to the surface of the initial quantum dot core.
In the step S01, it is preferable that the initial quantum dot core is configured to be mixed with the organic carboxylic acid in a solution. Preferably, in order to uniformly disperse the initial quantum dot cores in the solvent (the initial quantum dot cores are individually present in the solution and keep a proper distance from each other), good conditions are provided for shell growth on the surface of the initial quantum dot cores, and a shell with good dispersibility and uniform thickness is obtained, wherein in the solution of the initial quantum dot cores, the ratio of the mass of the initial quantum dot cores to the volume of the solvent is 10mg: (5-15 ml).
In the step S01, it is preferable that in the step of mixing the initial quantum dot core with an organic carboxylic acid, the initial quantum dot core is dispersed in a solution containing the organic carboxylic acid so that the mass molar ratio of the quantum dot core to the organic carboxylic acid is 10mg (3 to 10mmol), and the initial quantum dot core is subjected to a surface modification treatment. In order to enable the organic carboxylic acid to be sufficiently bonded to the initial quantum dot core and reduce the defect state of the surface of the initial quantum dot core, the organic carboxylic acid reagent may be present in a certain excess amount, but the organic carboxylic acid reagent cannot be present in an excess amount, otherwise the viscosity is too high, the subsequent long shell rate is influenced, and the formation of a shell layer is not facilitated.
In one embodiment, in step S02, the step of preparing the shell layer on the surface of the initial quantum dot core is performed in a shell layer growth reaction system containing an organic carboxylic acid. Specifically, in one embodiment, when the organic carboxylic acid is added in excess in step S01, the organic carboxylic acid in the shell growth reaction system is derived from the organic carboxylic acid remaining in step S01, that is, the initial quantum dot core is mixed with the organic carboxylic acid, so that the organic carboxylic acid is bonded to the surface of the initial quantum dot core; when the organic carboxylic acid added in the step S01 is not excessive, or when the organic carboxylic acid added in the step S01 is excessive but insufficient as the shell layer grows, an appropriate amount of the organic carboxylic acid may be additionally added to the shell layer growth reaction system during the preparation of the shell layer on the surface of the initial quantum dot core, so that a sufficient amount of the carboxylic acid is bonded to the surface of the growing shell layer, and the prepared quantum dot has good monodispersity. Of course, it should be noted here that, the organic carboxylic acid ligand is generated after the pyrolysis of the selected specific kinds of shell source anion precursor (such as the complex precursor formed by nonmetal simple substances of Te, Se, S, P, etc. and oleic acid) and shell source cation precursor (zinc oleate, cadmium oleate, etc.), and it is because the part of organic ligand generated after the pyrolysis is not enough to sufficiently modify (especially with the increase of the shell thickness) the surface of the growing shell, it is therefore necessary to perform shell layer growth in a reaction system for shell layer growth containing an organic carboxylic acid derived from an organic carboxylic acid remaining in the step of mixing the initial quantum dot core with an organic carboxylic acid to bond the organic carboxylic acid to the surface of the initial quantum dot core, and/or in the process of shell layer growth, adding a proper amount of organic carboxylic acid into the shell layer growth reaction system.
In one embodiment, in step S02, the shell growth reaction system refers to a reaction material system applied during the shell growth on the surface of the initial quantum dot core; in the embodiment of the invention, the shell source precursor can be injected into the solution containing the initial quantum dot core for one-time shell layer growth; in yet another embodiment of the present invention, multiple shell layer growth may be performed by injecting the shell source precursor into the solution containing the initial quantum dot core or the solution system for shell layer growth multiple times. Specifically, a shell source precursor is added into the initial quantum dot core to carry out first shell layer growth, and a first shell layer is prepared; further, adding a shell source precursor to the first shell layer for secondary shell layer growth, and preparing a second shell layer on the surface of the first shell layer; repeating the steps, and growing the N-th shell layer to prepare the N-th shell layer. In the embodiment, the organic carboxylic acid, the shell source anion precursor and the shell source cation precursor in the shell growth reaction system are combined on the surface of each shell layer, so that the material has good monodispersity after each shell layer is prepared, and the material is favorable for subsequent shell layer growth or has better dispersion performance when being used as a product.
In an embodiment of the present invention, the shell source precursor includes a shell source cation precursor and a shell source anion precursor. Wherein the shell source cation precursor is at least one of organic metal carboxylate formed by oxide or metal salt of Cd, Zn, Pb, Ag, Hg, Fe, In, Al and other metals and organic carboxylic acid. Further, the shell source cation precursor is selected from zinc oleate, lead oleate, silver oleate, mercury oleate, indium oleate, copper oleate, iron oleate, manganese oleate, aluminum oleate, zinc stearate, lead stearate, silver stearate, mercury stearate, indium stearate, copper stearate, iron stearate, manganese stearate, aluminum stearate, zinc myristate, lead myristate, silver myristate, mercury myristate, indium myristate, copper myristate, iron myristate, manganese myristate, aluminum myristate, zinc palmitate, lead palmitate, silver palmitate, mercury palmitate, indium palmitate, copper palmitate, zinc laurate, silver laurate, manganese laurate, aluminum laurate, zinc laurate, manganese laurate, aluminum laurate, zinc laurate, copper laurate, manganese laurate, aluminum laurate, zinc laurate, copper laurate, aluminum laurate, zinc laurate, copper laurate, zinc oleate, zinc, At least one of zinc stearate, lead stearate, silver stearate, mercury stearate, indium stearate, copper stearate, iron stearate, manganese stearate, and aluminum stearate, but not limited thereto. In the embodiment of the invention, the shell source anion precursor is prepared by dispersing nonmetal simple substances such as Te, Se, S, P and the like into an anion complex formed in an organic molecule. When the shell source anion precursor is an anion complex formed by non-metal simple substances such as Te, Se, S, P and the like and organic molecules, the organic molecules are selected from at least one of trioctylphosphine, tributylphosphine, oleic acid and octadecene, but the invention is not limited thereto. In the embodiment of the present invention, if the anionic precursor is thiol, the organic molecule containing non-metal atoms is an organic molecule containing a mercapto (-HS) functional group with a single functional group (e.g., octadecanethiol, heptadecanethiol, hexadecanethiol, pentadecanethiol, tetradecanethiol, tridecanethiol, dodecanethiol, octanethiol, etc., but not limited thereto).
In the embodiment of the present invention, the choice of the shell source is not limited, and preferably should be satisfied that the band gap of the obtained shell layer is larger than that of the initial quantum dot core.
Preferably, in the embodiment of the present invention, the shell source cation precursor is selected from at least one of organometallic carboxylates of Cd, Zn and Pb, and the shell source anion precursor is selected from an anionic complex formed by dispersing Te, Se and S into an organic molecule, or thiol.
In the embodiment of the invention, the adding sequence of the shell cation precursor and the shell anion precursor is not strictly limited every time the shell source is injected for shell growth. For example, the shell source is a mixed precursor solution in which a shell cation precursor and a shell anion precursor are dispersed; the method of adding the shell source may be: respectively injecting a cation precursor and an anion precursor into a solvent to obtain a cation precursor solution and an anion precursor solution, and injecting a shell cation precursor solution and then injecting a shell anion precursor solution; or respectively injecting the cation precursor and the anion precursor into a solvent to obtain a cation precursor solution and an anion precursor solution, and injecting the shell anion precursor solution and then injecting the shell cation precursor solution; or injecting the cation precursor and the anion precursor into a solvent to prepare a mixed solution containing the cation precursor and the anion precursor, and injecting the mixed solution into a solution containing the initial quantum dot core or a solution system with a grown shell layer.
Preferably, the concentration range of the active shell source cation precursor solution is (0.5-1.5 mmol/ml); the concentration range of the active shell source anion precursor solution is (0.5-1.5 mmol/ml). The appropriate concentration is beneficial to uniformly combining the shell source cation precursor and the shell source anion precursor on the surface of the initial quantum dot core, and the uniform and stable shell layer is formed by crystallization.
Preferably, the shell source precursor is injected into a solution containing the initial quantum dot core or a solution system for shell layer growth according to the mass ratio of the shell source cation precursor to the initial quantum dot core being (1-1.5 mmol):10mg and/or the mass ratio of the shell source anion precursor to the initial quantum dot core being (1-1.5 mmol):10 mg. The method is beneficial to the uniform and stable combination of the anion precursor and the cation precursor on the surface of the initial quantum dot core, and a shell layer with proper thickness is obtained.
Furthermore, the temperature of the shell layer prepared on the surface of the modified initial quantum dot core is 150-320 ℃, and the shell is favorably crystallized from the precursor of the anions and the cations within the temperature range, and the stability of the quantum dots is not influenced.
In step S03, in an embodiment, the solution system after the shell growth reaction is completed is mixed with an organic phosphine, so that the organic phosphine is combined with the non-metal atoms on the surface of the quantum dot shell, the defect state on the surface of the core-shell nanocrystal is reduced, and the fluorescence intensity of the core-shell quantum dot is further improved.
In the step S03, in an embodiment, the solution system after the shell growth reaction is completed is mixed with the organic phosphine, and heated at the temperature of 100-320 ℃ for 10-60 min. Under the condition, the organic phosphine is combined with the non-metal atoms on the surface of the quantum dot shell layer, so that the defect state of the surface of the core-shell nanocrystal is reduced, and the fluorescence intensity of the quantum dot with the core-shell structure is further improved. If the mixing treatment temperature and/or time of the solution system after the growth reaction of the organic phosphine and the shell layer is over low and/or over short, the effect of passivating the anion vacancy by the organic phosphine is not obvious, even the passivation effect cannot be exerted, and further the fluorescence intensity of the core-shell structure nanocrystal cannot be improved; if the mixing treatment temperature of the solution system after the growth reaction of the organic phosphine and the shell layer is finished is too high, the organic phosphine is easy to volatilize, the modification treatment effect is influenced, and the stability of the structure of the core-shell structure nanocrystal is influenced by the high-temperature condition.
In the step S03, in the step of mixing and heating the system after the shell growth reaction is completed with the organophosphine, preferably, the core-shell structure quantum dots are dispersed into the solution containing the organophosphine according to the molar mass ratio of the organophosphine to the initial quantum dot core (2-5 mmol):10 mg. If the content of the organic phosphine is too low, the effect of passivating the anion vacancy is not obvious, and the fluorescence intensity of the core-shell structure quantum dot is difficult to obviously improve. If the content of the organic phosphine is too high, the film forming performance of the core-shell structure nanocrystal in the preparation of the film layer can be influenced.
In step S03, in an embodiment, the system after the shell layer growth reaction is completed is mixed with organic amine, so that the organic amine can complex with the remaining shell source cation precursor in the solution system after the shell layer growth reaction is completed, thereby reducing the freezing point of the remaining shell source cation precursor in the solution system, and further facilitating subsequent cleaning and purity improvement of the quantum dot mixed solution, so that when the prepared quantum dot is used for manufacturing a device film, the influence of the remaining cation precursor impurities in the quantum dot solution with the core-shell structure on the device stability can be effectively avoided, and the film forming quality of the quantum dot solid film can be improved.
In the step S03, in an embodiment, the solution system after the shell growth reaction is completed is mixed with organic amine, and heated at 80-320 ℃ for 10-60 min. Under the condition, the organic amine is combined with the non-metal atoms on the surface of the quantum dot shell layer, so that the freezing point of the residual shell source cation precursor in the solution system is reduced, and the purity of the core-shell structure quantum dot is further improved. If the mixing temperature of the solution system after the growth reaction of the shell layer and the organic amine is too low and/or the time is too short, the effect of complexing the residual cation precursor by the organic amine is not obvious, and the purity of the core-shell structure quantum dot cannot be improved; if the temperature is too high and/or the time is too long, the high temperature condition can affect the stability of the core-shell structure quantum dot structure, such as ligand shedding.
In the step S03, the system after the shell growth reaction is completed is mixed with organic amine, so that the organic amine is bonded to the surface of the shell, and preferably, the core-shell structure quantum dots are dispersed into a solution containing the organic amine according to a molar mass ratio of the organic amine to the initial quantum dot core of (5-10 mmol):10 mg. If the content of the organic amine is too low, the effect of improving the purity of the core-shell structure quantum dot is not obvious. If the content of the organic amine is too high, the organic amine remaining after complexing with the residual cation precursor in the mixed solution of the core-shell structure quantum dots exchanges with the ligand on the surface of the core-shell structure quantum dots, and the organic amine ligand is unstable (the exchanged organic carboxylic acid is removed in the cleaning process) and is easy to fall off, so that defects are introduced into the falling position, and the photo-thermal stability, the fluorescence intensity and the solubility of the core-shell structure quantum dots are reduced.
Particularly preferably, the organic amine used as the post-treatment agent is selected from organic amines having 8 to 18 carbon atoms. Further, the organic amine reagent is selected from linear organic amines containing single amino, and the linear organic amines are favorable for reducing steric hindrance and promoting the organic amines to be combined on the surface of the shell layer. Specifically, the organic amine reagent can be at least one selected from oleylamine, trioctylamine, dodecylamine, tetradecylamine, hexadecylamine and octadecylamine.
In step S03, in an embodiment, the solution system after the shell growth reaction is completed is mixed with the mixed solution of organic amine and organic phosphine, so that the organic phosphine, the organic amine and the non-metal atoms on the surface of the quantum dot shell are combined, and the fluorescence intensity and the purity of the quantum dot with the core-shell structure are improved.
In the step S03, in an embodiment, the solution system after the growth reaction of the shell is completed is mixed with the mixed solution of organic amine and organic phosphine, and heated at 80-320 ℃ for 10-90 min. Under the condition, the organic amine and the organic phosphine are combined with the non-metal atoms on the surface of the quantum dot shell layer, so that the purity and the fluorescence intensity of the quantum dot with the core-shell structure are improved. If the mixing temperature and/or time of the solution system after the growth reaction of the shell layer and the mixed solution of the organic amine and the organic phosphine are too low and/or too short, the effect of complexing the residual cation precursor by the organic amine and the organic phosphine is not obvious, and the purity and the fluorescence intensity of the core-shell structure quantum dot cannot be improved; if the temperature is too high and/or the time is too long, the high temperature condition can affect the stability of the core-shell structure quantum dot structure, such as ligand shedding.
In the step S03, in the step of mixing and heating the solution system after the shell growth reaction is completed and the mixed solution of organic amine and organic phosphine, the solution system after the shell growth reaction is completed is mixed with the mixed solution of organic amine and organic phosphine according to the molar mass ratio of the organic amine to the initial quantum dot core of (5-10 mmol):10mg and the molar mass ratio of the organic phosphine to the initial quantum dot core of (2-5 mmol):10 mg. The effect of the organophosphine, organoamine content is as described hereinbefore.
The embodiment of the invention also provides the core-shell structure quantum dot prepared by the method.
Further, the embodiment of the invention provides application of the core-shell structure quantum dot in the fields of optical devices, optical films, core-shell structure quantum dot ink, glue, biological probes and the like.
Specifically, the optical device includes, but is not limited to, a quantum dot light emitting diode, and a quantum dot sensitized cell.
Specifically, the optical film includes, but is not limited to, quantum dot light-blocking diaphragms, quantum dot light-emitting tubes, and the like.
Specifically, the core-shell structure quantum dot ink includes, but is not limited to, an ink in which quantum dots and other different chemical solvents are combined in different proportions.
Specifically, the glue includes, but is not limited to, glue formed by combining quantum dots with a core-shell structure with other different chemical agents according to different viscosity ratios.
Specifically, the biological probe is formed by modifying a specific substance on the surface of a quantum dot.
The following description will be given with reference to specific examples.
Example 1
A preparation method of quantum dots comprises the following steps:
1. preparation of cadmium selenide (CdSe) initial quantum dot core,
11) preparing a cadmium precursor: 0.25mmol of CdO, 0.5mmol of octadecylphosphonic acid and 3g of trioctylphosphine are taken together and added to a 50ml three-neck flask, heated to 380 ℃ to dissolve it and to obtain a clear and transparent solution, and kept at this temperature;
12) preparation of Se precursor: 0.5mmol of Se source solution is taken and stirred in 1ml of trioctylphosphine at room temperature until the solution is clear for later use;
13) preparation of CdSe initial quantum dots: injecting 1ml of trioctylphosphine solution into the container 11) before injecting the Se precursor, injecting the Se precursor for reacting for 30s when the temperature of the solution is returned to 380 ℃, then injecting 10ml of octadecyl quenching reaction, cooling to room temperature, and cleaning;
14) washing and purifying the CdSe initial quantum dots: and adding 30ml of acetone into the quantum dot mixed solution, performing centrifugal separation on the quantum dots, and dispersing the CdSe initial quantum dots subjected to centrifugal separation into 10ml of n-hexane for later use.
2. Processing the cadmium selenide (CdSe) initial quantum dot core,
taking initial quantum dots by nucleation 2ml of CdSe initial quantum dots solution dispersed in n-hexane prepared in step 1) is added into octadecane solution containing 1ml of oleic acid and 10ml of oleic acid, heated to 150 ℃ and exhausted for 20min, and the temperature of the CdSe solution is raised to 300 ℃.
Preparing CdSe/ZnS core-shell quantum dots,
31) preparation of a ZnS shell source: dispersing 1mmol of zinc oleate precursor and 1.5mmol of 1-octadecanethiol in 10ml of octadecane solution, stirring and heating at 80 ℃ to ensure that turbid liquid becomes clear, and cooling to room temperature for later use;
32) and (3) growing a ZnS shell layer: injecting the ZnS shell source prepared in the step 31) into the CdSe initial quantum dot core solution prepared in the step 2) at a dropping rate of 6ml/h for shell growing, wherein the injection time is 80 min;
33) and cooling the prepared CdSe/ZnS quantum dot solution to room temperature without any post-treatment after the circulation reaction is finished.
And 4, purifying the CdSe/ZnS core-shell quantum dots.
Adding a proper amount of ethyl acetate and ethanol into the quantum dot mixed solution prepared in the step 3) to carry out centrifugal separation on the CdSe/ZnS quantum dot solution, dispersing the CdSe/ZnS quantum dot solution obtained by centrifugation into a proper amount of chloroform solution again to disperse the CdSe/ZnS quantum dot solution, then adding acetone and methanol into the solution to carry out precipitation and centrifugal separation, and repeating the step once; and finally, carrying out vacuum drying on the obtained CdSe/ZnS quantum dots.
The CdSe/ZnS quantum dots prepared by the method of the embodiment have improved solubility, and the corresponding effect is that the monodispersity of the CdSe/ZnS core-shell quantum dots can be improved; and testing the absorbance of the CdSe/ZnS solution (with the concentration of 0.05mg/ml) by using an ultraviolet visible fluorescence spectrum, wherein the absorbance value ranges from 0.86 to 1.53.
Example 2
A preparation method of a core-shell structure quantum dot comprises the following steps:
the preparation of the initial quantum dot core of CdS is as follows:
11) cadmium oleate { Cd (OA)2Preparing a precursor, namely preparing a precursor,
adding 1mmol of cadmium oxide (CdO), 4ml of Oleic Acid (OA) and 10ml of Octadecene (ODE) into a three-neck flask, vacuumizing for 30mins at normal temperature, then heating to 180 ℃, discharging argon for 60mins, maintaining the vacuum for 30mins at 180 ℃, and cooling to room temperature for later use;
12) preparation of selenium (Se) precursor: weighing 10mmol Se, adding into 10ml Trioctylphosphine Oxide (TOP), heating to 170 deg.C for 30min, and cooling to 140 deg.C;
13) preparation of sulfur (S-TOP) precursor: weighing 20mmol S, adding into 10ml Trioctylphosphine Oxide (TOP), heating to 170 deg.C for 30min, and cooling to 140 deg.C;
14) preparation of sulfur (S-ODE) precursor: weighing 5mmol S, adding to 10ml Octadecene (ODE), heating to 110 deg.C for 60min, and maintaining at 110 deg.C;
15) cadmium oleate { Cd (OA) in the step 11)2Heating the precursor to 250 ℃, extracting 2ml of S-ODE precursor in the step 14), injecting the S-ODE precursor into a three-neck flask for reaction for 10min to prepare CdS initial quantum dot nuclei, and dispersing the prepared CdS initial quantum dot nuclei in n-hexane through centrifugal separation and drying.
The CdS/CdSe core-shell quantum dots are prepared as follows:
21) preparation of CdSe shell source: 1mmol of cadmium oleate precursor and 1.5mmol of Se-TOP are taken and dispersed in 10ml of octadecyl solution, and then stirred for standby.
22) Dispersing 10mg CdS initial quantum dot core in 1ml OA and 10ml ODE, exhausting gas at normal temperature for 20min, heating to 300 deg.C,
23) and (3) growing a CdS shell: dropwise adding the CdS shell source prepared in the step 21) into the CdSe initial quantum dot core solution in the step 1) at a dropwise adding rate of 6ml/h for shell growing, wherein the dropwise adding time is 80min
24) Adding a precipitator into the CdS/CdSe core-shell quantum dot mixed solution prepared in the step 23), and dispersing the prepared CdS/CdSe core-shell quantum dots in normal hexane through centrifugal separation and drying.
3. The oil-soluble red CdS/CdSe/CdS are prepared as follows:
31) preparing a CdS shell source: 1mmol of cadmium oleate precursor and 1.5mmol of 1-dodecyl mercaptan are dispersed in 10ml of octadecyl solution, stirred and heated at 80 ℃ to ensure that turbid liquid becomes clear, and then cooled to room temperature for later use.
32) Dispersing 10mg CdS/CdSe core-shell structure quantum dots in 1ml OA and 10ml ODE, exhausting gas at normal temperature for 20min, heating to 300 ℃,
33) and (3) growing a CdS shell: and (3) dropwise adding the CdS shell source prepared in the step 31) into the CdS/CdSe core-shell structure quantum dot solution in the step 2) at a dropwise adding rate of 6ml/h for shell growing, wherein the dropwise adding time is 80 min.
34) And cooling the prepared CdS/CdSe/CdS quantum dot solution to room temperature without any post-treatment after the circulation reaction is finished.
4. And purifying the oil-soluble red CdS/CdSe/CdS.
41) Adding a proper amount of ethyl acetate and ethanol into the quantum dot mixed solution in the step 3) to carry out centrifugal separation on the CdS/CdSe/Cd quantum well quantum dot solution, dispersing the CdS/CdSe/CdS quantum well quantum dot solution obtained by centrifugation into a proper amount of chloroform solution again to disperse the solution, then adding acetone and methanol into the solution to carry out precipitation centrifugal separation, and repeating the step once; and finally, carrying out vacuum drying on the CdS/CdSe/CdS quantum well quantum dots.
The solubility of the CdS/CdSe/CdS quantum dots prepared by the method of the embodiment is improved, and the corresponding effect is that the monodispersity of the CdS/CdSe/CdS core-shell quantum dots is improved; and testing the absorbance of the CdS/CdSe/CdS solution (with the concentration of 0.05mg/ml) by using an ultraviolet visible fluorescence spectrum, wherein the absorbance value ranges from 0.85 to 1.62.
Example 3
A preparation method of a core-shell structure quantum dot comprises the following steps:
1. preparation of cadmium selenide (CdSe) initial quantum dot core,
11) preparing a cadmium precursor: 0.25mmol of CdO, 0.5mmol of octadecylphosphonic acid and 3g of trioctylphosphine are taken together and added to a 50ml three-neck flask, heated to 380 ℃ to dissolve it and to obtain a clear and transparent solution, and kept at this temperature;
12) preparation of Se precursor: 0.5mmol of Se source solution is taken and stirred in 1ml of trioctylphosphine at room temperature until the solution is clear for later use;
13) preparation of CdSe quantum dots: injecting 1ml of trioctylphosphine solution into the step 11) before injecting the Se precursor in the step 12), injecting the Se precursor for reacting for 30s when the temperature of the solution is returned to 380 ℃, then injecting 10ml of octadecyl into the solution for quenching reaction, cooling the solution to room temperature, and cleaning the solution;
14) washing and purifying the CdSe initial quantum dots: and adding 30ml of acetone into the quantum dot mixed solution, performing centrifugal separation on the quantum dots, and dispersing the CdSe initial quantum dots subjected to centrifugal separation into 10ml of n-hexane for later use.
2. Processing of cadmium selenide (CdSe) initial quantum dot cores
Dispersing CdSe initial quantum dot core: taking 2ml of CdSe initial quantum dots dispersed in n-hexane prepared in the step 1), adding the CdSe initial quantum dots into an octadecane solution containing 1ml of oleic acid and 10ml of oleic acid, heating the CdSe initial quantum dot solution to 150 ℃, exhausting gas for 20min to remove the redundant n-hexane solution in the solution, and then raising the temperature of the CdSe solution to 300 ℃.
Preparing CdSe/CdS core-shell quantum dots,
31) preparing a CdS shell source: 1mmol of cadmium oleate precursor and 1.5mmol of 1-dodecyl mercaptan are dispersed in 10ml of octadecane solution together, stirred and heated at 80 ℃ to ensure that turbid liquid becomes clear, and then cooled to room temperature for later use;
32) and (3) growing a CdS shell: dropwise adding the CdS shell source prepared in the step 31) into the CdSe initial quantum dot core solution in the step 2) at a dropwise adding rate of 6ml/h for shell growing, wherein the dropwise adding time is 80 min;
33) after the growth of the circulating long shell is finished, adding 5mmol of oleylamine into the mixed solution, and curing the mixed solution at 300 ℃ for 60 min;
34) and cooling the prepared CdSe/CdS quantum dot solution to room temperature without any post-treatment after the circulation reaction is finished.
4, purifying the CdSe/CdS core-shell quantum dots,
adding a proper amount of ethyl acetate and ethanol into the quantum dot mixed solution obtained in the step 3) to carry out centrifugal separation on the CdSe/CdS quantum dot solution, dispersing the CdSe/CdS quantum dot solution obtained by centrifugation into a proper amount of chloroform solution again to disperse the chloroform solution, then adding acetone and methanol into the solution to carry out precipitation and centrifugal separation, and repeating the step once; and finally, carrying out vacuum drying on the obtained CdSe/CdS quantum dots.
The CdSe/CdS quantum dots prepared by the method of the embodiment have reduced fluorescence intensity and improved stability after being prepared into devices. Measuring the Quantum Yield (QY) of the CdSe/CdS solution at room temperature by an integrating sphere (Edinburgh-FS 5) of a fluorescence spectrometer, wherein the range of the QY value is 70-79%; after 30 days of testing, the External Quantum Efficiency (EQE) of the QLED device is reduced by 1-5%.
Example 4
A preparation method of a core-shell structure quantum dot comprises the following steps:
1. preparation of cadmium selenide (CdSe) initial quantum dot core,
11) preparing a cadmium precursor: 0.25mmol of CdO, 0.5mmol of octadecylphosphonic acid and 3g of trioctylphosphine are taken together and added to a 50ml three-neck flask, heated to 380 ℃ to dissolve it and to obtain a clear and transparent solution, and kept at this temperature;
12) preparation of Se precursor: 0.5mmol of Se source solution is taken and stirred in 1ml of trioctylphosphine at room temperature until the solution is clear for later use;
13) preparation of CdSe quantum dots: injecting 1ml of trioctylphosphine solution into the Se precursor 11) before injecting the Se precursor in the step 12), injecting the Se precursor for reacting for 30s when the temperature of the solution is recovered to 380 ℃, then injecting 10ml of octadecyl quenching reaction, cooling to room temperature, and cleaning;
14) washing and purifying the CdSe initial quantum dots: and adding 30ml of acetone into the quantum dot mixed solution, performing centrifugal separation on the quantum dots, and dispersing the CdSe initial quantum dots subjected to centrifugal separation into 10ml of n-hexane for later use.
2. Processing of cadmium selenide (CdSe) initial quantum dot cores
Dispersing CdSe initial quantum dot core: taking 2ml of CdSe initial quantum dots prepared and dispersed in n-hexane in 1, adding the CdSe initial quantum dots into an octadecane solution containing 1ml of oleic acid and 10ml of oleic acid, firstly heating the CdSe initial quantum dot solution to 150 ℃, exhausting gas for 20min to remove the redundant n-hexane solution in the solution, and then raising the temperature of the CdSe solution to 300 ℃.
Preparing CdSe/CdS core-shell quantum dots,
31) preparing a CdS shell source: 1mmol of cadmium oleate precursor and 1.5mmol of 1-dodecyl mercaptan are dispersed in 10ml of octadecane solution together, stirred and heated at 80 ℃ to ensure that turbid liquid becomes clear, and then cooled to room temperature for later use;
32) and (3) growing a CdS shell: taking the CdS shell source prepared in the step 31), and dropwise adding the CdS shell source into the CdSe initial quantum dot core solution in the step 2 at a dropwise adding rate of 6ml/h for shell growing, wherein the dropwise adding time is 80 min;
33) after the growth of the circulating long shell is finished, adding 5mmol of trioctylphosphine into the mixed solution, and curing for 60min at 300 ℃;
34) and cooling the prepared CdSe/CdS quantum dot solution to room temperature without any post-treatment after the circulation reaction is finished.
4, purifying the CdSe/CdS core-shell quantum dots,
adding a proper amount of ethyl acetate and ethanol into the quantum dot mixed solution obtained in the step 3) to carry out centrifugal separation on the CdSe/CdS quantum dot solution, dispersing the CdSe/CdS quantum dot solution obtained by centrifugation into a proper amount of chloroform solution again to disperse the chloroform solution, then adding acetone and methanol into the solution to carry out precipitation and centrifugal separation, and repeating the step once; and finally, carrying out vacuum drying on the obtained CdSe/CdS quantum dots.
The CdSe/CdS quantum dots prepared by the method of the embodiment can further improve the fluorescence intensity of the quantum dots. The Quantum Yield (QY) of the solution at room temperature was measured by an integrating sphere (Edinburgh-FS 5) of a fluorescence spectrometer with the QY value ranging from 78 to 89%.
Example 5
A preparation method of a core-shell structure quantum dot comprises the following steps:
1. preparation of cadmium selenide (CdSe) initial quantum dot core,
11) preparing a cadmium precursor: 0.25mmol of CdO, 0.5mmol of octadecylphosphonic acid and 3g of trioctylphosphine are taken together and added to a 50ml three-neck flask, heated to 380 ℃ to dissolve it and to obtain a clear and transparent solution, and kept at this temperature;
12) preparation of Se precursor: 0.5mmol of Se source solution is taken and stirred in 1ml of trioctylphosphine at room temperature until the solution is clear for later use;
13) preparation of CdSe quantum dots: injecting 1ml of trioctylphosphine solution into the step 11) before injecting the Se precursor in the step 12), injecting the Se precursor for reacting for 30s when the temperature of the solution is recovered to 380 ℃, then injecting 10ml of octadecyl quenching reaction, cooling to room temperature, and cleaning;
14) and (3) cleaning and purifying the CdSe quantum dots: 30ml of acetone is added into the quantum dot mixed solution to centrifugally separate the quantum dots, and the centrifugally separated CdSe quantum dots are dispersed in 10ml of n-hexane for later use.
2. Processing of cadmium selenide (CdSe) initial quantum dot cores
Dispersing CdSe initial quantum dot core: taking 2ml of CdSe initial quantum dots dispersed in n-hexane prepared in the step 1), adding the CdSe initial quantum dots into an octadecane solution containing 1ml of oleic acid and 10ml of oleic acid, heating the CdSe initial quantum dot solution to 150 ℃, exhausting gas for 20min to remove the redundant n-hexane solution in the solution, and then raising the temperature of the CdSe solution to 300 ℃.
Preparing CdSe/CdS core-shell quantum dots,
31) preparing a CdS shell source: 1mmol of cadmium oleate precursor and 1.5mmol of 1-octadecanethiol are taken to be dispersed in 10ml of octadecane solution together, and then the solution is stirred and heated at 80 ℃ to ensure that turbid liquid becomes clear and then is cooled to room temperature for standby;
32) and (3) growing a CdS shell: dropwise adding the CdS shell source prepared in the step 31) into the CdSe initial quantum dot core solution in the step 2) at a dropwise adding rate of 6ml/h for shell growing, wherein the dropwise adding time is 80 min;
33) after the growth of the circulating long shell is finished, adding 1ml of oleylamine mixed solution of 2mmol of tributylphosphine into the mixed solution, and curing for 60min at 300 ℃;
34) and cooling the prepared CdSe/CdS initial quantum dot solution to room temperature without any post-treatment after the circulation reaction is finished.
4, purifying the CdSe/CdS core-shell quantum dots,
adding a proper amount of ethyl acetate and ethanol into the quantum dot mixed solution obtained in the step 3) to carry out centrifugal separation on the CdSe/CdS quantum dot solution, dispersing the CdSe/CdS quantum dot solution obtained by centrifugation into a proper amount of chloroform solution again to disperse the chloroform solution, then adding acetone and methanol into the solution to carry out precipitation and centrifugal separation, and repeating the step once; and finally, carrying out vacuum drying on the obtained CdSe/CdS quantum dots.
The CdSe/CdS quantum dots prepared by the method of the embodiment can improve the stability. The Quantum Yield (QY) of the solution after standing for 30 days at room temperature was measured by an integrating sphere (Edinburgh-FS 5) of a fluorescence spectrometer, where the QY value ranged from 83-91%.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (11)
1. The preparation method of the quantum dot is characterized by comprising the following steps:
providing an initial quantum dot core, mixing the initial quantum dot core with an organic carboxylic acid, and bonding the organic carboxylic acid to the surface of the initial quantum dot core;
preparing a shell layer on the surface of the initial quantum dot core, wherein the step of preparing the shell layer on the surface of the initial quantum dot core is carried out in a shell layer growth reaction system containing organic carboxylic acid;
mixing and heating a solution system after the growth reaction of the shell layer is finished with organic amine;
or mixing the system after the growth reaction of the shell layer is finished with the organic phosphine and heating;
or mixing the solution system after the shell growth reaction is finished with the mixed solution of organic amine and organic phosphine, and heating.
2. The method of claim 1, wherein the organic carboxylic acid in the shell growth reaction system is derived from the organic carboxylic acid remaining from the step of mixing the initial quantum dot core with the organic carboxylic acid to bind the organic carboxylic acid to the surface of the initial quantum dot core;
and/or the organic carboxylic acid in the shell layer growth reaction system is derived from organic acid which is additionally added into the shell layer growth reaction system in the process of preparing the shell layer on the surface of the initial quantum dot core.
3. The method of claim 1, wherein in the step of mixing the initial quantum dot core with an organic carboxylic acid to bond the organic carboxylic acid to the surface of the initial quantum dot core, the initial quantum dot core is mixed with the organic carboxylic acid in a molar mass ratio of the initial quantum dot core to the organic carboxylic acid of 10mg (3 to 10 mmol).
4. The method of preparing a quantum dot according to claim 1, wherein the initial quantum dot core is mixed with an organic carboxylic acid and heated at a temperature of 80 to 150 ℃ for 20 to 60min to bind the organic carboxylic acid to the surface of the initial quantum dot core.
5. The preparation method of the quantum dot, according to claim 1, characterized in that in the step of mixing and heating the solution system after the shell growth reaction is completed with the organic amine, the solution system after the shell growth reaction is mixed with the organic amine according to the molar mass ratio of the organic amine to the initial quantum dot core of (5-10 mmol):10 mg;
or in the step of mixing and heating the system after the shell growth reaction is finished and the organic phosphine, mixing the solution system after the shell growth reaction is finished and the organic phosphine according to the molar mass ratio of the organic phosphine to the initial quantum dot core of (2-5 mmol):10 mg;
or in the step of mixing and heating the solution system after the shell growth reaction is finished and the mixed solution of organic amine and organic phosphine, mixing the solution system after the shell growth reaction is finished and the mixed solution of organic amine and organic phosphine according to the molar mass ratio of the organic amine to the initial quantum dot core of (5-10 mmol) to 10mg and the molar mass ratio of the organic phosphine to the initial quantum dot core of (2-5 mmol) to 10 mg.
6. The method for preparing the quantum dot according to any one of claims 1 to 5, wherein the solution system after the shell growth reaction is completed is mixed with a mixed solution of organic amine and organic phosphine, and the mixed solution is mixed and heated for 10 to 90min at a temperature of 80 to 320 ℃.
7. The method for preparing a quantum dot according to any one of claims 1 to 5, wherein the solution system is mixed with the organic amine after the shell growth reaction is completed, and the mixture is mixed and treated at 80 to 320 ℃ for 30 to 90min and heated.
8. The method for preparing a quantum dot according to any one of claims 1 to 5, wherein the solution system is mixed with the organic phosphine after the shell growth reaction is completed, and the mixture is treated for 10 to 60min at a temperature of 100 ℃ and 320 ℃ and heated.
9. The method for preparing a quantum dot according to any one of claims 1 to 5, wherein the organic carboxylic acid is one or more selected from organic carboxylic acids having 8 to 18 carbon atoms;
and/or the organic amine is selected from one or more organic amines with the carbon atom number of 8-18;
and/or the organic phosphine is at least one of trioctylphosphine and tributylphosphine.
10. The method for preparing a quantum dot according to claim 9, wherein when the organic carboxylic acid is one or more selected from the group consisting of organic carboxylic acids having 8 to 18 carbon atoms, the organic acid is selected from a linear organic acid having a single carboxyl group; and/or
When the organic amine is selected from one or more of organic amines with the carbon atom number of 8-18, the organic amine is selected from linear organic amines containing single carboxyl.
11. The method for preparing a quantum dot according to claim 10, wherein when the organic acid is selected from linear organic acids having a single carboxyl group, the organic acid is selected from at least one of oleic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid; and/or
When the organic amine is selected from straight-chain organic amines containing single carboxyl, the organic amine is selected from at least one of oleylamine, trioctylamine, dodecylamine, tetradecylamine, hexadecylamine and octadecylamine.
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