CN113025317A - Quantum dot composite material and preparation method thereof - Google Patents

Quantum dot composite material and preparation method thereof Download PDF

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CN113025317A
CN113025317A CN201911354257.6A CN201911354257A CN113025317A CN 113025317 A CN113025317 A CN 113025317A CN 201911354257 A CN201911354257 A CN 201911354257A CN 113025317 A CN113025317 A CN 113025317A
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quantum dot
composite material
quantum dots
polysilazane
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聂志文
刘文勇
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TCL Corp
TCL Research America Inc
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Abstract

The invention provides a preparation method of a quantum dot composite material, which comprises the following steps: preparing a mixed system of quantum dots, polysilazane and organic alcohol in an inert atmosphere; heating the obtained mixed system for reaction to cause alcoholysis of the polysilazane; and separating the product system to obtain the quantum dot composite material. The preparation method of the quantum dot composite material provided by the invention is simple and easy to operate, and more importantly, the monodispersity and stability of the quantum dots can be obviously improved by adopting the technology on the premise of not influencing the optical performance of the quantum dots, so that the preparation method has important significance for wide application of the quantum dots.

Description

Quantum dot composite material and preparation method thereof
Technical Field
The invention belongs to the technical field of quantum dot materials, and particularly relates to a quantum dot composite material and a preparation method thereof.
Background
Quantum dots, also known as semiconductor nanocrystals, are semiconductor materials with particle sizes smaller than or close to the Bohr radius, and generally consist of elements from groups II-VI or III-V. Since electrons and holes are completely bound in three dimensional directions, the quantum confinement effect is strong, and the quantum confinement effect is represented by a plurality of excellent properties. The method specifically comprises the following steps: the luminescent wavelength is continuously adjustable, the peak width is narrow, the luminescent efficiency is high, the service life is long, and the solution processability is good. Due to the excellent properties, the quantum dots are widely applied to the fields of illumination display, solar cells, biological imaging and the like.
The premise of really realizing the large-scale application of the quantum dots is to ensure that the quantum dots have good monodispersity and stability. On one hand, the quantum dots have very large specific surface area due to small size, and a large number of defect states exist on the surface, and the defect states are easy to be used as adsorption centers of water and oxygen in air in the using process, so that the optical performance is reduced. On the other hand, the surface of a high-quality quantum dot is usually coated with some ligands, and the ligands can passivate and stabilize the surface of the quantum dot to some extent. However, since these ligands are usually only weakly adhered to the surface of the quantum dot, they are very easy to fall off, so that voids are left on the surface of the quantum dot, and the existence of the voids may cause the aggregation and even precipitation of the quantum dot, which greatly affects the monodispersity thereof. Therefore, the problems of poor monodispersity and poor stability of the quantum dots greatly limit the wide use of the quantum dots. At present, the method commonly used for improving the monodispersity and stability of the quantum dots is to coat the quantum dots with organic polymers or silicon dioxide. However, these methods have more or less major disadvantages. Such as: the water resistance of the quantum dots can be improved to a certain extent after the quantum dots are coated with the organic polymer, but the diffusion rate of oxygen in most organic polymers is high, and the stability of an organic polymer framework is poor. Thus, such organic polymer-coated quantum dots generally have poor photo-oxidation and stability. In addition, an alkaline reagent is generally required to be used as a catalyst in the process of coating the silicon dioxide, and the existence of the catalyst can directly contact with the quantum dots, so that the fluorescence of the quantum dots is attenuated, and even the fluorescence is quenched. Accordingly, the prior art is in need of improvement and development.
Disclosure of Invention
The invention aims to provide a quantum dot composite material and a preparation method thereof, and aims to solve the problem that the dispersibility and stability of quantum dots prepared in the prior art are influenced.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a preparation method of a quantum dot composite material, which comprises the following steps:
preparing a mixed system of quantum dots, polysilazane and organic alcohol in an inert atmosphere;
heating the obtained mixed system for reaction to cause alcoholysis of the polysilazane;
and separating the product system to obtain the quantum dot composite material.
The invention provides a quantum dot composite material, which contains quantum dot particles, wherein the quantum dot particles comprise quantum dots and inorganic polymer layers coated on the surfaces of the quantum dots, and the material of the inorganic polymer layers contains SiO2、SiNxAnd SiNxO。
The preparation method of the quantum dot composite material provided by the invention is characterized in that the quantum dot, polysilazane and organic alcohol are mixed and heated. Due to the polysilazane (-H)2The N in the-SiNH-) can be combined with cations on the surface of the quantum dot, and the polysilazane is adsorbed on the surface of the quantum dot. Furthermore, organic alcohol is used as a catalyst, and the polysilazane is subjected to alcoholysis reaction under the heating condition, so that the polysilazane alcoholysis inorganic polymer layer combined on the surface of the quantum dot is formed. Because the chemical activity of Si-N bond is high and the reaction activity with polar solvent is higher, the inorganic polymer layer obtained by the alcoholysis of polysilazane not only contains SiO2Mixed with SiNxAnd SiNxAnd O. Wherein, SiNxAnd SiNxOyThe quantum dot composite material has more excellent water, oxygen and thermal stability, so that the obtained quantum dot composite material has good stability and longer service life; and the quantum dot composite material has good monodispersity, and can prevent the problems of efficiency reduction and the like caused by aggregation or agglomeration and the like of quantum dots. In addition, the invention adopts an alcohol solvent as a catalyst, so that the direct contact between an alkaline catalyst used in the conventional coating process and the quantum dots can be effectively avoided, and the fluorescence attenuation is causedAnd even quenching of fluorescence.
In conclusion, the preparation method of the quantum dot composite material provided by the invention is simple and easy to operate, and more importantly, the monodispersity and stability of the quantum dots can be remarkably improved by adopting the technology on the premise of not influencing the optical performance of the quantum dots, so that the preparation method has important significance for wide application of the quantum dots.
The inorganic polymer layer on the surface of the quantum dot contains SiO in the quantum dot composite material provided by the invention2、SiNxAnd SiNxO, wherein, SiNxAnd SiNxOyThe quantum dot composite material has more excellent water, oxygen and thermal stability, so that the obtained quantum dot composite material has good stability and longer service life; and the quantum dot composite material has good monodispersity, and can prevent the problems of efficiency reduction and the like caused by aggregation or agglomeration and the like of quantum dots.
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Fig. 1 is a schematic flow chart of a preparation method of a quantum dot composite material provided by an embodiment of the invention.
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 weight of the related components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present invention as long as it is in accordance with the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiment of the present invention may be a unit of mass known in the chemical industry field, such as μ g, mg, g, and kg.
As shown in fig. 1, a first aspect of the embodiments of the present invention provides a method for preparing a quantum dot composite material, including the following steps:
s01, preparing a mixed system of quantum dots, polysilazane and organic alcohol in an inert atmosphere;
s02, carrying out heating reaction on the obtained mixed system to carry out alcoholysis on the polysilazane;
and S03, separating a product system to obtain the quantum dot composite material.
According to the preparation method of the quantum dot composite material provided by the embodiment of the invention, the quantum dots, the polysilazane and the organic alcohol are mixed and heated. Due to the polysilazane (-H)2The N in the-SiNH-) can be combined with cations on the surface of the quantum dot, and the polysilazane is adsorbed on the surface of the quantum dot. Furthermore, organic alcohol is used as a catalyst, and the polysilazane is subjected to alcoholysis reaction under the heating condition, so that the polysilazane alcoholysis inorganic polymer layer combined on the surface of the quantum dot is formed. Because the chemical activity of Si-N bond is high and the reaction activity with polar solvent is higher, the inorganic polymer layer obtained by the alcoholysis of polysilazane not only contains SiO2Mixed with SiNxAnd SiNxAnd O. Wherein, SiNxAnd SiNxOyThe quantum dot composite material has more excellent water, oxygen and thermal stability, so that the obtained quantum dot composite material has good stability and longer service life; and the quantum dot composite material has good monodispersity, and can prevent the problems of efficiency reduction and the like caused by aggregation or agglomeration and the like of quantum dots. In addition, the invention adopts an alcohol solvent as a catalyst, and can effectively avoid the problems of fluorescence attenuation and even fluorescence quenching caused by direct contact of an alkaline catalyst used in the conventional coating process and the quantum dots.
In summary, the preparation method of the quantum dot composite material provided by the embodiment of the invention is simple and easy to operate, and more importantly, by adopting the technology, the monodispersity and stability of the quantum dot can be remarkably improved on the premise of not influencing the optical performance of the quantum dot, so that the preparation method has important significance for wide application of the quantum dot.
Specifically, in step S01, the quantum dots may be single-core quantum dots or core-shell quantum dots. Specifically, the quantum dots are selected from at least one of group II-VI mononuclear semiconductor nanocrystals, group II-VI core-shell structure semiconductor nanocrystals, group III-V mononuclear semiconductor nanocrystals, group III-V core-shell structure semiconductor nanocrystals, group IV-VI mononuclear semiconductor nanocrystals and group IV-VI core-shell structure semiconductor nanocrystals, but not limited thereto. In particular, the quantum dots are selected from group II-VI CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe; GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaGaAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InInInInNP, InInInAlN, InLNSb, InAlGaInPS, InAlGaAs, InAPs; group IV-VI quantum dots comprising SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, or a combination of two or more of the foregoing quantum dots.
As a preferred embodiment, the preparation method of the quantum dot is as follows: and dispersing the quantum dots in the mesoporous alumina under an inert atmosphere to obtain the mesoporous alumina coated quantum dots. The quantum dots prepared by the method are dispersed in the pore structure of the mesoporous alumina, so that the distance between the adjacent quantum dots is increased, and the dispersibility of the quantum dots is further improved. Furthermore, the mesoporous alumina coated quantum dots can be dissolved in a non-polar solvent to obtain a quantum dot solution. In some embodiments, the non-polar solvent includes, but is not limited to, at least one of n-hexane, n-heptane, cyclohexane, chloroform, chlorobenzene, toluene.
Preferably, the pore diameter of the mesoporous alumina is 2 nm-20 nm, so that the quantum dots are uniformly dispersed in the pores of the mesoporous alumina. If the pore diameter of the mesoporous alumina is too small, the quantum dots are difficult to enter a pore structure, so that the dispersibility of the mesoporous alumina is improved; if the pore diameter of the mesoporous alumina is too large, a plurality of quantum dots may be agglomerated in a mesoporous alumina pore structure, and the dispersibility of the quantum dots may be reduced.
In a preferred embodiment, the mass ratio of the mesoporous alumina to the mixed system is 10-100: 1. If the mass of the mesoporous alumina is too small, part of the quantum dots cannot be well dispersed in the mesoporous alumina, so that the dispersibility is reduced; if the quality of the mesoporous alumina is too high, the quantum dots in the single mesoporous alumina are not distributed enough, thereby affecting the overall luminous efficiency.
In the embodiment of the invention, in order to avoid the influence of water and oxygen permeation on the stability of the quantum dots in the reaction process, organic alcohol is used as a catalyst, and after polysilazane is combined on the surfaces of the quantum dots, the polysilazane is alcoholyzed into an inorganic polymer. In some embodiments, the organic alcohol is selected from alkyl alcohols having less than or equal to 20 carbon atoms, which is detrimental to the alcoholysis reaction when the chain length is too long and the number of carbon atoms exceeds 20. In some embodiments, the organic alcohol includes, but is not limited to, methanol, ethanol, isopropanol.
In order to facilitate the polysilazane to be fully bonded on the surface of the quantum dot (polysilazane (-H) before alcoholysis reaction2-SiNH-) can be combined with cations on the surface of the quantum dot), and in the step of configuring the mixed system, preferably, the quantum dot and the polysilazane are mixed, and then the organic alcohol is added. Firstly, preparing a mixed solution of quantum dots and polysilazane to combine the polysilazane and the quantum dots; then add intoAnd (5) mixing organic alcohol.
In the step of preparing the mixed solution of the quantum dots and the polysilazane, the quantum dot solution and the polysilazane solution can be respectively prepared and then mixed; alternatively, a solution of one solute may be prepared and then the other solute added. In a preferred embodiment, in the step of preparing the mixed solution of the quantum dots and the polysilazane, the quantum dot solution and the polysilazane solution may be prepared separately and then mixed, thereby improving the solubility of the two solutions and allowing the polysilazane and the quantum dots to be more sufficiently combined. The solvent in the quantum dot solution is a nonpolar solvent capable of dissolving the quantum dots, and includes but is not limited to at least one of n-hexane, n-heptane, cyclohexane, chloroform, chlorobenzene, and toluene. The polysilazane solution is formed by forming polysilazane in an organic solvent, wherein the solvent for dissolving the polysilazane includes but is not limited to at least one of xylene and toluene.
In some embodiments, the quantum dot solution, the polysilazane solution, and the organic alcohol are mixed to prepare a mixed solution of the three. The quantum dots and the polysilazane can be dissolved separately, so that the solubility of the quantum dots and the polysilazane can be improved, and the combination sufficiency of the quantum dots and the polysilazane can be improved.
In a preferred embodiment, in the step of mixing and treating the quantum dot solution, the polysilazane solution and the organic alcohol, the quantum dot solution, the polysilazane solution and the organic alcohol are mixed and treated in a ratio of a volume of the organic alcohol to a total volume of the quantum dot solution and the polysilazane solution being 0.01-0.5: 1. According to the proportion that the volume of the organic alcohol and the total volume ratio of the quantum dot solution to the polysilazane solution are 0.01-0.5: 1, when the quantum dot solution, the polysilazane solution and the organic alcohol are mixed and treated, the alcoholysis reaction of polysilazane can be promoted on the basis of ensuring the solubility of quantum dots. If the content of the organic alcohol is too low, the ratio of the volume of the organic alcohol to the total volume of the quantum dot solution and the polysilazane solution is less than 0.01:1, which is not beneficial to the reaction of the alcoholysis reaction of polysilazane; if the content of the organic alcohol is too high, and the ratio of the volume of the organic alcohol to the total volume of the quantum dot solution and the polysilazane solution is greater than 0.5:1, the quantum dots are precipitated due to the organic alcohol serving as a polar solvent, and the coating rate of the quantum dots is affected.
In addition to the above-described examples, in the step of preparing a mixed system of quantum dots, polysilazane, and organic alcohol, aluminum isopropoxide was added and mixed with the quantum dots, polysilazane, and organic alcohol to prepare a mixed system. As a preferred embodiment, the quantum dots are dispersed in mesoporous alumina under an inert atmosphere to obtain mesoporous alumina coated quantum dots; dissolving the mesoporous alumina coated quantum dots in a non-polar solvent to obtain a quantum dot solution dispersed in a mesoporous matrix; then adding polysilazane solution, organic alcohol and aluminum isopropoxide for mixing treatment to prepare a mixed system. When the quantum dots are mesoporous alumina coated quantum dots, the mesoporous alumina-based quantum dots can be coated as a whole by the aluminum isopropoxide in such a way, and then the aluminum oxide is formed through alcoholysis, so that the overall stability is improved, and the overall composite quantum dot material is ensured to have excellent monodispersity and good stability. In some preferred embodiments, the mesoporous alumina has a pore size of 2nm to 20 nm. In some preferred embodiments, the mass ratio of the mesoporous alumina to the mixed system is 10-100: 1.
Preferably, the quantum dot solution and the polysilazane solution are mixed to fully combine the polysilazane on the surface of the quantum dot, and then the aluminum isopropoxide and the organic alcohol are added to alcoholyze the polysilazane to form the solution containing SiO2、SiNxAnd SiNxMixture of O (inorganic polymer), alcoholysis of the aluminum isopropoxide to alumina. The inorganic polymer and the alumina are mixed to construct a mixed layer, and the mixed layer is coated on the surface of the composite particle of the quantum dot based on the mesoporous alumina, so that the stability of the composite particle can be further improved. In a preferred embodiment, in the step of mixing the aluminum isopropoxide with the quantum dots, the polysilazane, and the organic alcohol, the mass ratio of the aluminum isopropoxide to the quantum dots is 0.1-10: 10And adding the aluminum isopropoxide and the quantum dot solution. If the quality of the aluminum isopropoxide is too high, an excessively thick aluminum oxide layer is easily formed, thereby reducing the light emitting efficiency; if the mass of the aluminum isopropoxide is too small, the aluminum isopropoxide is easy to be coated incompletely, and the stability of the whole quantum dot is not improved.
Further, a mixed system containing the aluminum isopropoxide, the quantum dot solution, the polysilazane solution, and the organic alcohol is heated to react, thereby alcoholyzing the polysilazane and the aluminum isopropoxide bonded to the surface of the quantum dot into an inorganic substance.
In the embodiment of the invention, the step of configuring the mixed system of the quantum dots, the polysilazane and the organic alcohol is carried out in the inert atmosphere, so as to avoid the influence of water and oxygen permeation on the stability of the quantum dots in the subsequent alcoholysis reaction process. The inert atmosphere includes, but is not limited to, a nitrogen atmosphere, an argon atmosphere, or a vacuum atmosphere.
In the step S02, the mixed system is heated at a temperature to react, and under the action of the heating strips, the polysilazane is alcoholyzed into an inorganic polymer under the catalytic action of the organic alcohol, and the inorganic polymer is coated on the surface of the quantum dot. In some embodiments, the temperature of the heat treatment is 80 ℃ to 350 ℃. Under the temperature condition, the polysilazane is subjected to alcoholysis under the action of organic alcohol to obtain an inorganic polymer layer, and the inorganic polymer layer not only contains SiO2Mixed with SiNxAnd SiNxAnd O. Wherein, SiNxAnd SiNxOyThe quantum dot composite material has more excellent water, oxygen and thermal stability, so that the obtained quantum dot composite material has good stability and longer service life; and the quantum dot composite material has good monodispersity, and can prevent the problems of efficiency reduction and the like caused by aggregation or agglomeration and the like of quantum dots.
In some embodiments, the mixed system formed by the quantum dots, the polysilazane and the organic alcohol is heated and reacted at the temperature of 80-350 ℃, and the heating and reacting time is 2 minutes-24 hours.
In some embodiments, the mixed system is a mixed system of quantum dots, polysilazane, aluminum isopropoxide, and an organic alcohol; wherein, the quantum dots are mesoporous alumina coated quantum dots. Further, the temperature for heating and reacting the mixed system is 200-300 ℃. If the temperature of the heating reaction is lower than 200 ℃, the alcoholysis of the aluminum isopropoxide is insufficient, and the quantum dots, particularly the quantum dots based on the mesoporous alumina, cannot be coated as a whole, which is not beneficial to improving the overall stability of the quantum dots, particularly the quantum dots based on the mesoporous alumina.
In step S03, after the reaction is completed, the product system is separated. Preferably, the method for separating the product system comprises the following steps: and centrifuging the product system at the rotating speed of 7000-12000 rpm for 5-10 min, discarding the supernatant, and collecting the precipitate. In this way, the precipitate can be fully collected under efficient centrifugation conditions.
In some embodiments, the mixed system is a mixed system of quantum dots, polysilazane, aluminum isopropoxide, and an organic alcohol; after heating and alcoholysis reaction, preferably before centrifugal separation of a product system, dissolving the product system by using normal hexane or chloroform, and then placing the product system under the condition that the rotating speed is 4000-8000 rpm for centrifugal separation for 2-10 min; and after the supernatant is discarded, adding normal hexane or chloroform into the precipitate, and continuing to carry out centrifugal separation for 2-5 times to obtain the quantum dot composite material. Because the size of the prepared quantum dot composite material is relatively large, in the embodiment, no additional precipitator is added, and the quantum dot composite material can be separated from other unreacted substances or byproducts only through centrifugal separation. Then, the supernatant is discarded, and n-hexane or chloroform is added for better purposes of adding unreacted substances or byproducts in the solvent product, thereby achieving the purpose of purifying the quantum dot composite material.
Further, the quantum dot composite material collected after the centrifugation treatment is dried, the drying mode is not strictly limited, and the quantum dot composite material can be dried for 10-24 hours, specifically 12 hours, under a vacuum condition.
In a second aspect, embodiments of the present invention provide a quantum dot composite material including a quantumThe quantum dot particles at least comprise quantum dots and an inorganic polymer layer coated on the surfaces of the quantum dots, and the material of the inorganic polymer layer contains SiO2、SiNxAnd SiNxO。
In the quantum dot composite material provided by the embodiment of the invention, the inorganic polymer layer on the surface of the quantum dot contains SiO2、SiNxAnd SiNxO, wherein, SiNxAnd SiNxOyThe quantum dot composite material has more excellent water, oxygen and thermal stability, so that the obtained quantum dot composite material has good stability and longer service life; and the quantum dot composite material has good monodispersity, and can prevent the problems of efficiency reduction and the like caused by aggregation or agglomeration and the like of quantum dots.
In one embodiment, the quantum dot composite material contains quantum dot particles, the quantum dot particles are composed of quantum dots and an inorganic polymer layer coated on the surfaces of the quantum dots, and the material of the inorganic polymer layer contains SiO2、SiNxAnd SiNxO。
In a preferred embodiment, the quantum dot particles further comprise mesoporous alumina, and the quantum dots are dispersed in the pores of the mesoporous alumina, and the inorganic polymer layer is coated on the surface of the mesoporous alumina. Wherein the quantum dot particles are composed of quantum dots, mesoporous alumina and an inorganic polymer layer coated on the surface of the mesoporous alumina, and the material of the inorganic polymer layer contains SiO2、SiNxAnd SiNxAnd O. At this time, since the quantum dots are dispersed in the pores of the mesoporous alumina, the occurrence of agglomeration between the quantum dots can be prevented, and the dispersibility of the quantum dot composite material can be further improved.
In a further preferred embodiment, the quantum dot composite material is the quantum dot particle, the quantum dot particle comprises mesoporous alumina, the quantum dots are dispersed in the pores of the mesoporous alumina, the inorganic polymer layer is coated on the surface of the mesoporous alumina, and the inorganic polymer layer of the quantum dot particle contains alumina. Namely theThe material of the inorganic polymer layer simultaneously contains SiO2、SiNx、SiNxO and alumina. The inorganic polymer layer thus formed is formed by strong alumina and SiO2、SiNx、SiNxAnd O together coats the composite particles with enhanced dispersion performance, thereby improving the stability of the composite particles with better dispersion performance.
The quantum dot composite material provided by the embodiment of the invention can be prepared by the method.
The following description will be given with reference to specific examples.
Example 1
A preparation method of a quantum dot composite material comprises the following steps:
(1) under nitrogen atmosphere, mixing 10ml CdZnSe/ZnS quantum dot n-hexane solution with concentration of 30mg/ml and 20ml polysilazane xylene solution with concentration of 20mg/ml, adding 0.3ml ethanol solution, and reacting at 80 ℃ for 2 h.
(2) After the reaction was completed, the product was centrifuged at 7000rpm for 10min, and the supernatant was discarded. And finally, drying the precipitate for 2 hours in vacuum to obtain the quantum dot composite material.
The comparison group 1 is original CdZnSe/ZnS quantum dot solution.
Example 2
A preparation method of a quantum dot composite material comprises the following steps:
(1) under nitrogen atmosphere, CdZnSe/ZnSe/ZnS quantum dot n-heptane solution with volume of 10ml and concentration of 30mg/ml and polysilazane toluene solution with volume of 20ml and concentration of 10mg/ml are mixed, then 1.5ml methanol solution is added, and finally the mixture is placed at 120 ℃ for reaction for 2 h.
(2) After the reaction is finished, the product is centrifugally separated for 10min at 10000rpm, and the supernatant is discarded. And finally, drying the precipitate for 2 hours in vacuum to obtain the quantum dot composite material.
The comparison group 2 is original CdZnSe/ZnSe/ZnS quantum dot solution.
Example 3
A preparation method of a quantum dot composite material comprises the following steps:
(1) under nitrogen atmosphere, a cyclohexane solution of InP/ZnSeS quantum dots with a volume of 10ml and a concentration of 30mg/ml and a xylene solution of polysilazane with a volume of 20ml and a concentration of 30mg/ml are mixed, then 4.5ml of isopropanol solution is added, and finally the mixture is placed at 80 ℃ for reaction for 2 hours.
(2) After the reaction was completed, the product was centrifuged at 12000rpm for 10min, and the supernatant was discarded. And finally, drying the precipitate for 2 hours in vacuum to obtain the quantum dot composite material.
Control 3 was InP/ZnSeS quantum dot solution.
Example 4
A preparation method of a quantum dot composite material comprises the following steps:
(1) under nitrogen atmosphere, a chloroform solution of InP/ZnSe/ZnS quantum dots with a volume of 10ml and a concentration of 30mg/ml was mixed with a xylene solution of polysilazane with a volume of 20ml and a concentration of 40mg/ml, then 7.5ml of an ethanol solution was added, and finally the mixture was left to react at 120 ℃ for 2 hours.
(2) After the reaction was completed, the product was centrifuged at 12000rpm for 10min, and the supernatant was discarded. And finally, drying the precipitate for 2 hours in vacuum to obtain the quantum dot composite material.
The control group 4 is InP/ZnSe/ZnS quantum dot solution.
Example 5
A preparation method of a quantum dot composite material comprises the following steps:
(1) under the nitrogen atmosphere, 10ml of CdSe/CdS quantum dot n-hexane solution with the concentration of 30mg/ml and 20ml of polysilazane toluene solution with the concentration of 50mg/ml are mixed, 11.5ml of ethanol solution is added, and finally the mixture is placed at 100 ℃ for reaction for 2 hours.
(2) After the reaction was completed, the product was centrifuged at 12000rpm for 10min, and the supernatant was discarded. And finally, drying the precipitate for 2 hours in vacuum to obtain the quantum dot composite material.
Control 5 is a CdSe/CdS quantum dot solution.
Example 6
A preparation method of a quantum dot composite material comprises the following steps:
(1) under nitrogen atmosphere, 10ml of InP/ZnSeS quantum dot n-hexane solution with the concentration of 30mg/ml and 20ml of polysilazane toluene solution with the concentration of 60mg/ml are mixed, then 1.5ml of ethanol solution is added, and finally the mixture is placed at 100 ℃ for reaction for 2 hours.
(2) After the reaction was completed, the product was centrifuged at 12000rpm for 10min, and the supernatant was discarded. And finally, drying the precipitate for 2 hours in vacuum to obtain the quantum dot composite material.
Control 6 was InP/ZnSeS quantum dot solution.
Example 7
A preparation method of a quantum dot composite material comprises the following steps:
(1) under the nitrogen atmosphere, mixing 10ml of CdZnSe/ZnS quantum dot n-hexane solution with the concentration of 30mg/ml with 50mg of mesoporous alumina, and repeatedly stirring at room temperature for 30min to obtain the mesoporous alumina coated quantum dots, wherein the pore diameter of the mesoporous alumina is 2-20 nm.
(2) 20ml of 20mg/ml polysilazane solution in toluene and 15mg of aluminum isopropoxide were added to the step (1), 1.5ml of ethanol and 4ml of dodecanol solution were then added, and the mixture was left to react at 250 ℃ for 2 hours.
(3) After the reaction is finished, placing the product system at the rotating speed of 4000rpm for centrifugal separation for 4 min; and (3) discarding the supernatant, adding chloroform into the precipitate, continuously performing centrifugal separation for 3 times, and finally drying under vacuum for 12 hours to obtain the final quantum dot composite material.
The control group 7 is a CdZnSe/ZnS quantum dot solution.
Example 8
A preparation method of a quantum dot composite material comprises the following steps:
(1) mixing 10ml of cyclohexane solution of CdZnSe/ZnS quantum dots with the concentration of 30mg/ml with 50mg of mesoporous alumina under the nitrogen atmosphere, and repeatedly stirring at room temperature for 30min to obtain the mesoporous alumina coated quantum dots, wherein the pore diameter of the mesoporous alumina is 2-20 nm.
(2) 20ml of polysilazane solution at a concentration of 20mg/ml in toluene and 15mg of aluminum isopropoxide were added to step (1), 1.5ml of isopropanol and 4ml of dodecanol solution were then added, and the mixture was left to react at 250 ℃ for 2 hours.
(3) And after the reaction is finished, placing the product system at the rotation speed of 4000rpm for centrifugal separation for 4min, discarding the supernatant, adding chloroform into the precipitate for continuous centrifugal separation for 3 times, and finally placing the precipitate in vacuum for drying for 12h to obtain the final quantum dot composite material.
The control group 8 is a CdZnSe/ZnS quantum dot solution.
The quantum dot composites prepared in examples 1 to 8 and the quantum dots of comparative examples 1 to 8 (corresponding to the quantum dots provided in step (1) of examples 1 to 8) were prepared as n-hexane solutions having a concentration of 20mg/mL, and continuously irradiated at 365nm for 24 hours. The solutions were tested for Quantum Yield (QY) and the results are shown in table 1 below.
TABLE 1
Figure BDA0002335460280000131
As can be seen from the above table, compared with the untreated quantum dot of the control group, the quantum dot composite material provided in the embodiments of the present invention has significantly improved luminous efficiency, because the inorganic polymer layer is formed on the surface of the quantum dot, and the inorganic polymer layer contains SiO2、SiNxAnd SiNxAnd O, the stability and the dispersibility of the quantum dot composite material are improved, so that the luminous efficiency of the quantum dot composite material is improved.
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 (14)

1. The preparation method of the quantum dot composite material is characterized by comprising the following steps of:
preparing a mixed system of quantum dots, polysilazane and organic alcohol in an inert atmosphere;
heating the obtained mixed system for reaction to cause alcoholysis of the polysilazane;
and separating the product system to obtain the quantum dot composite material.
2. The method for preparing a quantum dot composite material according to claim 1, wherein in the step of preparing a mixed system of the quantum dot, the polysilazane and the organic alcohol, the organic alcohol is added after the quantum dot and the polysilazane are mixed in a mass ratio of the polysilazane to the quantum dot of 0.1 to 20: 1.
3. The method of preparing a quantum dot composite material according to claim 1, wherein the temperature of the heat treatment is 80 ℃ to 350 ℃.
4. The method of claim 1, wherein the organic alcohol is selected from alkyl alcohols having 20 or less carbon atoms.
5. A method of preparing a quantum dot composite material according to any of claims 1 to 4, wherein the step of separating the product system comprises: and centrifuging the product system at the rotating speed of 7000-12000 rpm for 5-10 min, discarding the supernatant, and collecting the precipitate.
6. The method of preparing a quantum dot composite material according to claim 1, wherein the method of preparing the quantum dot is as follows: and dispersing the quantum dots in the mesoporous alumina under an inert atmosphere to obtain the mesoporous alumina coated quantum dots.
7. The method of claim 6, wherein the mesoporous alumina has a pore size of 2nm to 20 nm.
8. The preparation method of the quantum dot composite material according to claim 6, wherein the mass ratio of the mesoporous alumina to the mixed system is 10-100: 1.
9. The method for preparing a quantum dot composite material according to any one of claims 6 to 8, wherein in the step of preparing a mixed system of quantum dots, polysilazane and organic alcohol, aluminum isopropoxide is added and mixed with the quantum dots, the polysilazane and the organic alcohol to prepare the mixed system.
10. The method for preparing a quantum dot composite material according to claim 9, wherein in the step of adding aluminum isopropoxide and mixing with the quantum dots, the polysilazane and the organic alcohol, the aluminum isopropoxide and the quantum dots are added in a mass ratio of aluminum isopropoxide to quantum dots of 0.1 to 10: 10.
11. The preparation method of the quantum dot composite material according to any one of claims 6 to 8 and 10, wherein before the product system is separated, n-hexane or chloroform is adopted to dissolve the product system, and then the product system is placed under the condition that the rotating speed is 4000rpm to 8000rpm for centrifugal separation for 2 to 10 min; and after the supernatant is discarded, adding normal hexane or chloroform into the precipitate, and continuing to carry out centrifugal separation for 2-5 times to obtain the quantum dot composite material.
12. The quantum dot composite material is characterized by comprising quantum dot particles, wherein the quantum dot particles at least comprise quantum dots and an inorganic polymer layer coated on the surfaces of the quantum dots, and the material of the inorganic polymer layer contains SiO2、SiNxAnd SiNxO。
13. The quantum dot composite material of claim 12, wherein the quantum dot particles further comprise mesoporous alumina, and the quantum dots are dispersed in the pores of the mesoporous alumina, the inorganic polymer layer coating the surface of the mesoporous alumina.
14. The quantum dot composite of claim 12 or 13, wherein the inorganic polymer layer of the quantum dot particle comprises alumina.
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