CN102816564A - Preparation method and application for nano-composite luminescent material with high fluorescence efficiency and silicon dioxide coated quantum dots - Google Patents

Abstract

The invention discloses a preparation method of a nano-composite luminescent material coated with SiO ₂ quantum dots. A SiO ₂ shell layer is grown on the surface of the quantum dots through reverse-phase microemulsion polymerization and post-treatment including annealing treatment and ultraviolet light treatment is performed. , Realized the preparation of nanocomposite luminescent materials coated with SiO ₂ quantum dots. The quantum dots in the present invention can be single quantum dots or multiple quantum dots. The nanocomposite luminescent material coated with _SiO2 quantum dots prepared by the present invention can simultaneously meet the requirements of having a hydrophilic surface, having suitable surface functional groups, and having no biological toxicity, and has high fluorescence efficiency, so it can be used in the preparation of High-performance LED and other optoelectronic devices can also be used in the field of biological multicolor marking.

Description

Preparation method and application of a nanocomposite luminescent material coated with silicon dioxide and quantum dots with high fluorescence efficiency

technical field

The invention relates to a method for preparing a nanocomposite luminescent material, in particular to a method for preparing a nanocomposite luminescent material with high fluorescence efficiency and a silicon dioxide-coated quantum dot.

Background technique

Quantum dots (quantum dot, QD) are quasi-zero-dimensional nanomaterials, composed of a small number of atoms. Usually, quantum dots are nanoparticles composed of group II-VI or group III-V elements, whose size is smaller than or close to the exciton Bohr radius (generally, the diameter does not exceed 10nm). Because its electrons and holes are quantum confined, its energy The band structure becomes a discrete energy level structure with molecular characteristics, so it can emit fluorescence after being excited.

Due to their unique optoelectronic properties, quantum dots have important applications in the fields of biological multicolor labeling and optoelectronic devices. In order to obtain quantum dots with high monochromaticity and high fluorescence efficiency, a common method is to synthesize oil-soluble quantum dots in organic solutions by thermal injection. However, to apply quantum dots in the biological field, the following conditions need to be met: 1), have a hydrophilic surface; 2), have suitable surface functional groups; 3), have no biological toxicity (toxicity is mainly caused by surface ligands and Cd ²⁺ and other heavy metal ions are released).

In order to solve the above problems, the current commonly used method is to convert oil-soluble quantum dots into water-soluble quantum dots by ligand exchange, but this phase transfer process from oil-soluble quantum dots to water-soluble quantum dots is usually accompanied by fluorescence efficiency. substantial attenuation. In addition, although this method solves the problem of dissolving quantum dots in the water phase, it still does not solve the problem of possible biological toxicity caused by the release of heavy metal ions.

In recent years, it has been reported in the literature that nanocomposite luminescent particles are formed by coating the surface of oil-soluble quantum dots with a _SiO2 shell (which has a hydrophilic surface). This _SiO2 nanocomposite luminescent material coated with quantum dots will Has a hydrophilic surface. At the same time, literature has proved that the SiO ₂ shell can significantly reduce the escape of heavy metal ions and reduce biological toxicity. However, at present, the fluorescence efficiency of quantum dots coated with SiO ₂ will be greatly reduced. Therefore, how to maintain the fluorescence efficiency of nanocomposite luminescent materials coated with SiO ₂ quantum dots is of great significance for their applications in the fields of biology and photoelectric conversion.

Therefore, those skilled in the art are devoting themselves to developing a method for preparing a nanocomposite luminescent material coated with SiO ₂ quantum dots, so as to prepare a nanocomposite luminescent material coated with SiO ₂ quantum dots with high fluorescence efficiency.

Contents of the invention

In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a method for preparing _SiO coated quantum dot nanocomposite luminescent material, which grows on the surface of oil-soluble quantum dots by inverse microemulsion polymerization. A layer of _SiO2 shell layer, and then post-treatment to further improve the fluorescence efficiency of the nanocomposite luminescent material coated with _SiO2 quantum dots.

In order to achieve the above object, the invention provides a kind of _SiO The preparation method of the nano-composite luminescent material coated with quantum dots is characterized in that, comprising:

Step 1, dissolving the quantum dots in cyclohexane, or first dissolving the quantum dots in an organic reagent, and then dissolving them in cyclohexane;

Step 2, in the solution that step 1 obtains, add TEOS, tensio-active agent and catalyzer to carry out the inverse microemulsion polymerization reaction of catalysis;

Step 3, after the reaction has been carried out for a time (T1), acetone is added dropwise in the solution in which the reaction is carried out to terminate the reaction, and the solution in which the reaction has been terminated is centrifuged to obtain SiO ₂ coated Nanocomposite particles of quantum dots;

Step 4, wash the nanocomposite particles with ethanol and disperse them in ethanol or water, obtain the cleaned _SiO2 by centrifugation After the nanocomposite particles coated with the quantum dots are dissolved in n-butanol, put Enter the inner wall material and carry out annealing treatment in the hydrothermal reaction kettle that is polytetrafluoroethylene; The condition of described annealing treatment is: under stirring condition, oil bath, oil bath temperature (T), holding time (T2), drop with water cooling to room temperature; the annealed solution is centrifuged to obtain the annealed SiO ₂ nanocomposite particles coated with the quantum dots;

Step 5, washing the nanocomposite particles obtained in step 4 with ethanol and dispersing them in ethanol to obtain an ethanol solution containing the _SiO2 coated nanocomposite particles of the quantum dots after the annealing treatment;

Step 6. Put the ethanol solution obtained in step 5 under an ultraviolet lamp for ultraviolet light treatment, and the ultraviolet light time (T3) to obtain the _SiO2- coated compound that has undergone the ultraviolet light treatment and the annealing treatment. Ethanol solution of nanocomposite particles of quantum dots.

Further, the quantum dots are CdS, HgS, CdSe, CdTe, ZnSe, HgSe, ZnTe, ZnO, PbSe, HgTe, CaAs, InP, InCaAs, CdSe/ZnS, CdSe/ZnSe, CdS/ZnS, Cd/Ag2S, CdS/Cd(OH) ₂ , CdTe/ZnS, CdTe/CdS, CdSe/ZnSe, CdS/HgS, CdS/HgS/CdS, ZnS/CdS, ZnS/CdS/ZnS, ZnS/HgS/ZnS/CdS, CdSe/ Any one or more of CuSe, CdSeTe, CdSeTe/CdS/ZnS, Mn:CdS, Cu:CdS, Cu:ZnS, Mn:ZnS, Mn:ZnSe, Cu:ZnSe, Tb:CdS or Tb:ZnS combination.

Further, the size of the quantum dots is in the range of 1-10 nm.

Further, the organic reagent in the step 1 is hydrophobic, and the organic reagent is n-hexane, toluene, xylene, p-chlorotoluene, dichloromethane, chloroform, tetrachloromethane and petroleum ether reagents Any one of the reagents or a mixture of any two or more reagents.

Further, the surfactant in the second step is any one of surfactants NP5, NP9 and TritonX-100 or a combination of any two or more of them.

Further, the catalyst in the step 2 is any one or a combination of any two or more of the catalysts methylamine, ammonia water and dimethylamine.

Further, the time T1 in the step 3 is 20-80 hours.

Further, the temperature T of the oil bath in the step 4 is 50-90° C., and the holding time T2 is 0.5-2 hours.

Further, the time T3 in the step six is not less than 6 hours. .

In a preferred embodiment of the present invention, the quantum dots CdSe/CdS/ZnS, CdSeS/CdS, Cu:CdS/ZnS, Mn:ZnSe, CdTe/ZnS and CdSe are reacted in the quantum dots by inverse microemulsion polymerization. A SiO ₂ shell is grown on the surface and post-treated, including annealing and ultraviolet light treatment. Wherein the step of growing the _SiO2 shell layer on the surface of the quantum dots by inverse microemulsion polymerization is: dissolving the quantum dots in cyclohexane, or first dissolving the quantum dots in an organic reagent, and then dissolving them in cyclohexane; Add TEOS, surfactant and catalyst to the solution to carry out inverse microemulsion polymerization reaction; after the reaction time T1 (20h≤T1≤80h), add acetone dropwise to the solution to terminate the reaction, and centrifuge to obtain _SiO2 packets Nanocomposite particles coated with the quantum dots; these nanocomposite particles are washed with ethanol and dispersed in ethanol or water, and centrifuged to obtain the cleaned SiO ₂ nanocomposite particles coated with the quantum dots. The annealing treatment in the present invention is carried out in a hydrothermal reaction kettle, comprising the steps of dissolving the nanocomposite particles coated with the quantum dots in n _- butanol, and then putting them into a hydrothermal reaction kettle whose inner wall material is polytetrafluoroethylene Among them, the treatment conditions are: under stirring conditions, oil bath, oil bath temperature T (50 ° C ≤ T ≤ 90 ° C), holding time T2 (0.5h ≤ T1 ≤ 2h), cooled to room temperature in a water-cooled manner; centrifugal treatment of the solution to obtain annealed SiO ₂ coated nanocomposite particles of the quantum dots; wash these nanocomposite particles with ethanol and disperse them in ethanol to obtain annealed SiO ₂ coated nanocomposite particles of the quantum dots ethanol solution. The steps of the ultraviolet light treatment in the present invention are: place the ethanol solution under ultraviolet light for irradiation, and the ultraviolet light time T3 (T3≥6h), to obtain _SiO2 coated with the quantum dots through the ultraviolet light treatment and annealing treatment Ethanol solution of nanocomposite particles.

It can be seen that the preparation method of the nanocomposite luminescent material coated with _SiO2 of the present invention grows a _SiO2 shell layer on the surface of the quantum dots through inverse microemulsion polymerization and performs post-treatment including annealing treatment and ultraviolet light treatment. , successfully prepared nanocomposite luminescent materials coated with SiO ₂ quantum dots, wherein the SiO ₂ coated quantum dots can be a single type of quantum dots, or a combination of different types of quantum dots. The test of the fluorescent efficiency of the prepared various SiO ₂ coated quantum dot nanocomposite luminescent materials shows that through the SiO of the present invention comprising post-treatment of annealing treatment and ultraviolet light treatment The nanocomposite luminescent material _coated quantum dots The fluorescence efficiency has been greatly improved, the highest can reach 82.4% of the fluorescence efficiency of quantum dots not coated with SiO ₂ . In this way, the _SiO2 nanocomposite luminescent material coated with quantum dots prepared by the present invention can simultaneously meet the three requirements of having a hydrophilic surface, having suitable surface functional groups and having no biological toxicity, and has higher fluorescence efficiency, Therefore, it can be used to prepare high-performance photoelectric devices such as LEDs, and can also be used in the field of biological multicolor marking.

Detailed ways

Example 1

Step 1, dissolving quantum dots CdSe/CdS/ZnS in cyclohexane. Wherein, the quantum dot CdSe/CdS/ZnS is a quantum dot with a three-layer core-shell structure of CdSe/CdS/ZnS, and its fluorescence efficiency is 68%. Quantum dots CdSe/CdS/ZnS were dissolved in cyclohexane to obtain a 10 mL, 1 mM solution.

Step 2: In the solution obtained in step 1, add TEOS (tetraethylorthosilicate), a surfactant and a catalyst to carry out catalyzed inverse microemulsion polymerization. In the present embodiment, the concrete steps that carry out the inverse microemulsion polymerization reaction of catalysis are:

TEOS was added under agitation, followed by surfactants to form a microemulsion. Among them, 0.1 mL of TEOS was used, stirred for 10 min; NP5 was used as surfactant, and the dosage was 1 mL, stirred for 30 min. The catalyst is added under stirring condition to catalyze the inverse microemulsion polymerization reaction. Among them, methylamine was selected as the catalyst, and the dosage was 0.1 mL, and the stirring was continued under the condition of avoiding light.

Step 3, after the inverse microemulsion polymerization reaction of step 2 has been carried out for time T1, acetone is added dropwise in the solution in which the reaction is carried out to terminate the reaction, and the solution in which the reaction has been terminated is centrifuged to obtain _SiO coated quantum dots Nanocomposite particles of CdSe/CdS/ZnS. Wherein, the time T1 is set to 24h.

Step 4: Wash the nanocomposite particles obtained in Step 3 with ethanol and disperse them in ethanol, and obtain cleaned SiO ₂ coated quantum dot CdSe/CdS/ZnS nanocomposite particles by centrifugation. Experimental measurements show that the average particle diameter of the nanocomposite luminescent material is 32nm, its fluorescence intensity is 70.3% of the quantum dot CdSe/CdS/ZnS, and its fluorescence efficiency is 26%.

With above _- mentioned SiO After the nano-composite particle of coated quantum dot CdSe/CdS/ZnS is dissolved in n-butanol, put into the hydrothermal reactor that inner wall material is polytetrafluoroethylene and carry out annealing treatment, the condition of annealing treatment is: Under stirring conditions, oil bath, oil bath temperature T, holding time T2, cooled to room temperature by water cooling. In this embodiment, electromagnetic stirring is adopted, the temperature T of the oil bath is set at 70° C., and the holding time T2 is set at 1 h.

After the above annealing treatment, the solution was cooled to room temperature by water cooling and centrifuged to obtain the annealed SiO ₂ coated quantum dot CdSe/CdS/ZnS nanocomposite particles.

Step 5, cleaning the nanocomposite particles obtained in step 4 with ethanol and dispersing them in ethanol to obtain an ethanol solution containing nanocomposite particles of SiO ₂ coated quantum dots CdSe/CdS/ZnS after annealing treatment. The average particle size of the nanocomposite particles of SiO ₂ coated quantum dots CdSe/CdS/ZnS after annealing treatment does not change.

Step 6, place the ethanol solution obtained in step 5 under an ultraviolet lamp for ultraviolet light treatment, and the ultraviolet light time T3, to obtain _SiO2 coated quantum dots CdSe/CdS/ZnS nanocomposite particles through ultraviolet light treatment and annealing treatment ethanol solution. Among them, a portable ultraviolet lamp is used, the power is 8W, and the wavelength of ultraviolet light emitted by it is 365nm; the time T3 is set to 24h. The fluorescence efficiency of the SiO ₂ -coated quantum dot CdSe/CdS/ZnS nanocomposite luminescent material that has been treated by ultraviolet light and annealed is 56% according to experimental measurements.

Example 2

Step 1, dissolving the quantum dot CdSeS/CdS in cyclohexane. Wherein, the quantum dot is a quantum dot with a two-layer core-shell structure of CdSeS/CdS, and its fluorescence efficiency is 54%. Quantum dots CdSeS/CdS were dissolved in cyclohexane to obtain a 10 mL, 1 mM solution.

Step 2, in the solution that step 1 obtains, add TEOS, surfactant and catalyst to carry out the inverse microemulsion polymerization reaction of catalysis. In the present embodiment, the concrete steps that carry out the inverse microemulsion polymerization reaction of catalysis are:

TEOS was added under agitation, followed by a surfactant to form a microemulsion. Among them, 0.1 mL of TEOS was used, stirred for 10 min; NP5 was used as surfactant, and the dosage was 1 mL, stirred for 30 min. Then the catalyst is added under stirring condition to catalyze the inverse microemulsion polymerization reaction. Among them, methylamine is selected as the catalyst, and the dosage is 0.1 mL, and the stirring is continued under the condition of avoiding light.

Step 3, after the inverse microemulsion polymerization reaction of step 2 has been carried out for time T1, acetone is added dropwise in the solution in which the reaction is carried out to terminate the reaction, and the solution in which the reaction has been terminated is centrifuged to obtain _SiO coated quantum dots Nanocomposite particles of CdSeS/CdS. Wherein, the time T1 is set to 24h.

Step 4: Wash the nanocomposite particles obtained in Step 3 with ethanol and disperse them in ethanol, and obtain the cleaned SiO ₂ coated quantum dot CdSeS/CdS nanocomposite particles through centrifugation. Experimental measurement shows that the average particle diameter of the nanocomposite luminescent material is 38.1 nm.

After dissolving the _{nanocomposite} particles of SiO coated quantum dots CdSeS/CdS in n-butanol, put the inner wall material into a polytetrafluoroethylene hydrothermal reactor for annealing treatment. The conditions for annealing treatment are: stirring conditions Down, oil bath, oil bath temperature T, holding time T2, down to room temperature by water cooling. In this embodiment, electromagnetic stirring is adopted, the temperature T of the oil bath is set at 50° C., and the holding time T2 is set at 1 h.

After the above annealing treatment, the solution was cooled to room temperature by water cooling and centrifuged to obtain the annealed SiO ₂ coated quantum dot CdSeS/CdS nanocomposite particles.

Step 5, cleaning the nanocomposite particles obtained in step 4 with ethanol and dispersing them in ethanol to obtain an ethanol solution containing nanocomposite particles coated with SiO ₂ quantum dots CdSeS/CdS after annealing. The average particle size of the nanocomposite particles of SiO ₂ coated quantum dots CdSeS/CdS after annealing treatment does not change.

Step 6, place the ethanol solution that step 5 obtains under the ultraviolet lamp and carry out ultraviolet light treatment, the ultraviolet light time T3, obtain the ethanol containing the _{nanocomposite} particle of SiO coated quantum dot CdSeS/CdS through ultraviolet light treatment and annealing treatment solution. Among them, a portable ultraviolet lamp is used, the power is 16W, and the wavelength of ultraviolet light emitted by it is 365nm; the time T3 is set to 12h. The fluorescence efficiency of the SiO ₂ -coated quantum dot CdSeS/CdS nanocomposite luminescent material that has been treated by ultraviolet light and annealed is 43.2% according to experimental measurements.

Example 3

Step 1, the quantum dot Cu:CdS/ZnS is first dissolved in an organic reagent, and then dissolved in cyclohexane. Among them, the quantum dots are Cu:CdS/ZnS quantum dots with a two-layer core-shell structure of Cu-doped CdS/ZnS, and its fluorescence efficiency is 42.6%. The organic reagent is n-hexane, and the amount of cyclohexane is 9mL. Quantum dots Cu:CdS/ZnS were dissolved in n-hexane to obtain a 10 mL, 1 mM solution, and the solution was mixed with cyclohexane.

Step 2, in the solution that step 1 obtains, add TEOS, surfactant and catalyst to carry out the inverse microemulsion polymerization reaction of catalysis. In the present embodiment, the concrete steps that carry out the inverse microemulsion polymerization reaction of catalysis are:

The surfactant was added under agitation, followed by TEOS to form a microemulsion. Among them, NP9 was used as the surfactant, with an amount of 1 mL, and stirred for 30 min; 0.1 mL of TEOS was used, and stirred for 30 min. Then the catalyst is added under stirring condition to catalyze the inverse microemulsion polymerization reaction. Wherein, the catalyst is selected from dimethylamine, the dosage is 0.05mL, and the stirring is continued under the condition of avoiding light.

Step 3, after the inverse microemulsion polymerization reaction of step 2 has been carried out for time T1, acetone is added dropwise in the solution in which the reaction is carried out to terminate the reaction, and the solution in which the reaction has been terminated is centrifuged to obtain _SiO coated quantum dots Nanocomposite particles of Cu:CdS/ZnS. Wherein, the time T1 is set as 30h.

Step 4, wash the nanocomposite particles obtained in step 3 with ethanol and disperse them in ethanol, and obtain cleaned SiO ₂ coated quantum dot Cu:CdS/ZnS nanocomposite particles by centrifugation. Experimental measurement shows that the average particle diameter of the nanocomposite luminescent material is 41.4 nm.

With above _- mentioned SiO After the nano-composite particle of coating quantum dot Cu:CdS/ZnS is dissolved in n-butanol, put into the hydrothermal reactor that inner wall material is polytetrafluoroethylene and carry out annealing treatment, the condition of annealing treatment is: Under stirring conditions, oil bath, oil bath temperature T, holding time T2, cooled to room temperature by water cooling. In this embodiment, electromagnetic stirring is adopted, the temperature T of the oil bath is set at 80° C., and the holding time T2 is set at 1 h.

After the above annealing treatment, the solution was cooled to room temperature by water cooling and centrifuged to obtain SiO ₂ coated quantum dot Cu:CdS/ZnS nanocomposite particles after annealing treatment.

Step 5, cleaning the nanocomposite particles obtained in step 4 with ethanol and dispersing them in ethanol to obtain an ethanol solution containing nanocomposite particles of SiO ₂ coated quantum dots Cu:CdS/ZnS after annealing treatment. The average particle size of the nanocomposite particles of SiO ₂ coated quantum dots CdSeS/CdS after annealing treatment does not change.

Step 6, place the ethanol solution obtained in step 5 under a UV lamp for UV light treatment, and the UV light time T3, to obtain _SiO2 coated quantum dots Cu:CdS/ZnS nanocomposite particles through UV light treatment and annealing ethanol solution. Among them, a portable ultraviolet lamp is used, the power is 5W, and the wavelength of ultraviolet light emitted by it is 365nm; the time T3 is set to 40h. The fluorescence efficiency of the SiO ₂ -coated quantum dot Cu:CdS/ZnS nanocomposite luminescent material that has been treated by ultraviolet light and annealed is 24.3% according to experimental measurements.

Example 4

Step 1, the quantum dot Mn:ZnSe is first dissolved in an organic reagent, and then dissolved in cyclohexane. Wherein, the quantum dots are Mn:ZnSe quantum dots of Mn-doped ZnSe, and its fluorescence efficiency is 32.1%. The organic reagent is chloroform, and the amount of cyclohexane is 9mL. The quantum dot Mn:ZnSe was dissolved in chloroform to obtain a 1 mL, 10 mM solution, and the solution was mixed with cyclohexane.

Step 2, in the solution that step 1 obtains, add TEOS, surfactant and catalyst to carry out the inverse microemulsion polymerization reaction of catalysis. In the present embodiment, the concrete steps that carry out the inverse microemulsion polymerization reaction of catalysis are:

The surfactant was added under agitation, followed by TEOS to form a microemulsion. Among them, NP9 was used as the surfactant, with an amount of 1 mL, and stirred for 30 min; 0.1 mL of TEOS was used, and stirred for 30 min. Then the catalyst is added under stirring condition to catalyze the inverse microemulsion polymerization reaction. Among them, ammonia water was selected as the catalyst, and the dosage was 0.2 mL, and the stirring was continued under the condition of avoiding light.

Step 3, after the inverse microemulsion polymerization reaction of step 2 has been carried out for time T1, acetone is added dropwise in the solution in which the reaction is carried out to terminate the reaction, and the solution in which the reaction has been terminated is centrifuged to obtain _SiO coated quantum dots Nanocomposite particles of Mn:ZnSe. Wherein, the time T1 is set as 30h.

Step 4, wash the nanocomposite particles obtained in step 3 with ethanol and disperse them in ethanol, and obtain cleaned SiO ₂ coated quantum dot Mn:ZnSe nanocomposite particles through centrifugation. Experimental measurements show that the average particle diameter of the nanocomposite luminescent material is 28.7 nm.

With above-mentioned SiO After the nano _- composite particle of coating quantum dot Mn:ZnSe is dissolved in n-butanol, put into the hydrothermal reaction kettle that inner wall material is polytetrafluoroethylene and carry out annealing treatment, the condition of annealing treatment is: stirring condition Down, oil bath, oil bath temperature T, holding time T2, down to room temperature by water cooling. In this embodiment, electromagnetic stirring is adopted, the temperature T of the oil bath is set at 60° C., and the holding time T2 is set at 1 h.

After the above annealing treatment, the solution was cooled to room temperature by water cooling and centrifuged to obtain the annealed SiO ₂ coated quantum dot Mn:ZnSe nanocomposite particles.

Step 5, cleaning the nanocomposite particles obtained in step 4 with ethanol and dispersing them in ethanol to obtain an ethanol solution containing nanocomposite particles coated with SiO ₂ quantum dots Mn:ZnSe after annealing. After annealing, the average particle size of the SiO ₂ coated Mn:ZnSe nanocomposite particles remained unchanged.

Step 6, place the ethanol solution that step 5 obtains under the ultraviolet lamp and carry out ultraviolet light treatment, the ultraviolet light time T3, obtain the ethanol containing the _{nanocomposite} particles of SiO coated quantum dots Mn:ZnSe through ultraviolet light treatment and annealing treatment solution. Among them, a portable ultraviolet lamp is used, the power is 6W, and the wavelength of ultraviolet light emitted by it is 365nm; the time T3 is set to 18h. The fluorescence efficiency of the SiO ₂ -coated quantum dot Mn:ZnSe nanocomposite luminescent material that has been treated by ultraviolet light and annealed is 19.2% according to experimental measurements.

Example 5

Step 1, the quantum dot CdTe/ZnS is first dissolved in an organic reagent, and then dissolved in cyclohexane. Among them, the quantum dots are CdTe/ZnS quantum dots with a two-layer core-shell structure, and their fluorescence efficiency is 69.3%. The organic reagent is toluene, and the amount of cyclohexane is 9 mL. The quantum dot CdTe/ZnS was dissolved in toluene to obtain a 1 mL, 10 mM solution, which was mixed with cyclohexane.

Step 2, in the solution that step 1 obtains, add TEOS, surfactant and catalyst to carry out the inverse microemulsion polymerization reaction of catalysis. In the present embodiment, the specific steps of the inverse microemulsion polymerization of catalysis are:

The catalyst was added under stirring condition, the selected catalyst was methylamine, the dosage was 0.2mL, and the stirring was continued under the dark condition. The surfactant was then added under stirring, followed by TEOS to form a microemulsion. Among them, NP5 was used as the surfactant, with an amount of 1 mL, and stirred for 30 min; 0.1 mL of TEOS was used, and stirred for 30 min.

Step 3, after the inverse microemulsion polymerization reaction of step 2 has been carried out for time T1, acetone is added dropwise in the solution in which the reaction is carried out to terminate the reaction, and the solution in which the reaction has been terminated is centrifuged to obtain _SiO coated quantum dots Nanocomposite particles of CdTe/ZnS. Wherein, the time T1 is set as 48h.

Step 4, washing the nanocomposite particles obtained in step 3 with ethanol and dispersing them in ethanol, and obtaining cleaned SiO ₂ coated quantum dot CdTe/ZnS nanocomposite particles through centrifugation. Experimental measurement shows that the average particle diameter of the nanocomposite luminescent material is 37.2 nm.

After dissolving the _{nanocomposite} particles of SiO coated with quantum dots CdTe/ZnS in n-butanol, put them into a hydrothermal reactor whose inner wall material is polytetrafluoroethylene for annealing treatment. The conditions for annealing treatment are: stirring conditions Down, oil bath, oil bath temperature T, holding time T2, down to room temperature by water cooling. In this embodiment, electromagnetic stirring is adopted, the temperature T of the oil bath is set at 90° C., and the holding time T2 is set at 1 h.

After the above annealing treatment, the solution was cooled to room temperature by water cooling and centrifuged to obtain the annealed SiO ₂ coated quantum dot CdTe/ZnS nanocomposite particles.

Step 5, cleaning the nanocomposite particles obtained in step 4 with ethanol and dispersing them in ethanol to obtain an ethanol solution containing SiO ₂ coated quantum dot CdTe/ZnS nanocomposite particles after annealing treatment. After annealing, the average particle size of SiO ₂ coated quantum dots CdTe/ZnS nanocomposite particles remained unchanged.

Step 6, place the ethanol solution that step 5 obtains under the ultraviolet light and carry out ultraviolet light treatment, the ultraviolet light time T3, obtain the ethanol containing the _{nanocomposite} particles of SiO coated quantum dots CdTe/ZnS through ultraviolet light treatment and annealing treatment solution. Among them, a portable ultraviolet lamp is used, the power is 5W, and the wavelength of ultraviolet light emitted by it is 365nm; the time T3 is set to 30h. The fluorescence efficiency of the SiO ₂ -coated quantum dot CdTe/ZnS nanocomposite luminescent material that has been treated by ultraviolet light and annealed is 48.2% according to experimental measurements.

Example 6

Step 1, dissolving quantum dot CdSe in cyclohexane. Wherein, the quantum dots are CdSe quantum dots, the fluorescence efficiency of which is 39%; the dosage of cyclohexane is 6.5mL. Quantum dot CdSe was dissolved in cyclohexane to obtain a 10 mL, 1 mM solution.

Step 2, in the solution that step 1 obtains, add TEOS, surfactant and catalyst to carry out the inverse microemulsion polymerization reaction of catalysis. In the present embodiment, the concrete steps that carry out the inverse microemulsion polymerization reaction of catalysis are:

Add the catalyst under stirring condition, the selected catalyst is dimethylamine, the dosage is 0.05mL, and keep stirring under the dark condition. The surfactant was then added under stirring, followed by TEOS to form a microemulsion. Among them, Triton X-100 was used as surfactant, the dosage was 1.77mL, and stirred for 30min; 0.1mL of TEOS was used, and stirred for 30min.

Step 3, after the inverse microemulsion polymerization reaction of step 2 has been carried out for time T1, acetone is added dropwise in the solution in which the reaction is carried out to terminate the reaction, and the solution in which the reaction has been terminated is centrifuged to obtain _SiO coated quantum dots CdSe nanocomposite particles. Wherein, the time T1 is set as 48h.

Step 4: Wash the nanocomposite particles obtained in step 3 with ethanol and disperse them in ethanol, and obtain cleaned SiO ₂ coated quantum dot CdSe nanocomposite particles through centrifugation. Experimental measurement shows that the average particle diameter of the nanocomposite luminescent material is 34.5 nm.

With above-mentioned SiO After the nano _- composite particle of coating quantum dot CdSe is dissolved in n-butanol, put into the hydrothermal reactor that inner wall material is polytetrafluoroethylene and carry out annealing treatment, the condition of annealing treatment is: under stirring condition, Oil bath, oil bath temperature T, holding time T2, down to room temperature by water cooling. In this embodiment, electromagnetic stirring is adopted, the temperature T of the oil bath is set to 90° C., and the time T2 is set to 1 h.

The solution after the above annealing treatment was cooled to room temperature by water cooling and centrifuged to obtain the annealed SiO ₂ coated quantum dot CdSe nanocomposite particles.

Step 5, washing the nanocomposite particles obtained in step 4 with ethanol and dispersing them in ethanol to obtain an ethanol solution containing SiO ₂ coated quantum dot CdSe nanocomposite particles after annealing. The average particle size of the _SiO2- coated quantum dot CdSe nanocomposite particles after annealing was unchanged.

Step 6, place the ethanol solution obtained in step 5 under an ultraviolet lamp for ultraviolet light treatment, and the ultraviolet light time is T3, to obtain an ethanol solution containing SiO ₂ coated quantum dot CdSe nanocomposite particles after ultraviolet light treatment and annealing treatment. Among them, a portable ultraviolet lamp is used, the power is 15W, and the wavelength of ultraviolet light emitted by it is 365nm; the time T3 is set to 15h. The fluorescence efficiency of the SiO ₂ -coated quantum dot CdSe nanocomposite luminescent material that has been treated by ultraviolet light and annealed is 26.8% according to experimental measurements.

It should be noted that the quantum dots applicable to the preparation method of the _SiO2- coated quantum dot nanocomposite luminescent material of the present invention are not limited to the types of quantum dots provided in the examples here, but can be CdS, HgS, CdSe, CdTe, ZnSe, HgSe, ZnTe, ZnO, PbSe, HgTe, CaAs, InP, InCaAs, CdSe/ZnS, CdSe/ZnSe, CdS/ZnS, Cd/Ag ₂ S, CdS/Cd(OH) ₂ , CdTe/ZnS, CdTe/CdS, CdSe/ZnSe, CdS/HgS, CdS/HgS/CdS, ZnS/CdS, ZnS/CdS/ZnS, ZnS/HgS/ZnS/CdS, CdSe/CuSe, CdSeTe, CdSeTe/CdS/ZnS, Mn: Any one of CdS, Cu:CdS, Cu:ZnS, Mn:ZnS, Mn:ZnSe, Cu:ZnSe, Tb:CdS or Tb:ZnS, or a combination of any two or more of these quantum dots. For the latter case, two or more of these quantum dots can be arbitrarily selected and mixed in a desired ratio.

The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection defined by the claims.

Claims (9)

1. SiO ₂The preparation method of the nano combined luminescent material of coated quantum dots is characterized in that, comprising:

Step 1, quantum dot is dissolved in hexanaphthene, perhaps earlier said quantum dot is dissolved in the organic reagent, and then is dissolved in the hexanaphthene;

Step 2, in the solution that step 1 obtains, add TEOS, tensio-active agent and catalyzer to carry out catalytic conversed phase micro emulsion copolymerization reaction;

Step 3, after the time (T1) has been carried out in said reaction, in the solution that carries out said reaction, drip acetone to stop said reaction, the solution that has stopped said reaction is carried out centrifugal treating, obtain SiO ₂Coat the Nano composite granules of said quantum dot;

Step 4, clean said Nano composite granules and it is scattered in ethanol or the water, obtain SiO through cleaning through centrifugal treating with ethanol ₂After coating the Nano composite granules of said quantum dot and it being dissolved in propyl carbinol, the hydrothermal reaction kettle of putting into inner-wall material and be tetrafluoroethylene carries out anneal; The condition of said anneal is: under the agitation condition, oil bath, oil bath temperature (T) and soaking time (T2), reduce to room temperature with water-cooling pattern; Solution to accomplishing said anneal carries out centrifugal treating, obtains the said SiO through said anneal ₂Coat the Nano composite granules of said quantum dot;

Step 5, the said Nano composite granules that obtains with ethanol cleaning step four also are scattered in it in ethanol, obtain containing the said SiO through said anneal ₂Coat the ethanolic soln of the Nano composite granules of said quantum dot;

Step 6, the said ethanolic soln that step 5 is obtained place and carry out ultraviolet lighting under the uv lamp and handle, and the ultraviolet lighting time (T3), obtain containing through said ultraviolet lighting and handle and the said SiO of said anneal ₂Coat the ethanolic soln of the Nano composite granules of said quantum dot.

2. SiO as claimed in claim 1 ₂The preparation method of the nano combined luminescent material of coated quantum dots; Wherein said quantum dot is CdS, HgS, CdSe, CdTe, ZnSe, HgSe, ZnTe, ZnO, PbSe, HgTe, CaAs, InP, InCaAs, CdSe/ZnS, CdSe/ZnSe, CdS/ZnS, Cd/Ag ₂S, CdS/Cd (OH) ₂, any one or multiple combination among CdTe/ZnS, CdTe/CdS, CdSe/ZnSe, CdS/HgS, CdS/HgS/CdS, ZnS/CdS, ZnS/CdS/ZnS, ZnS/HgS/ZnS/CdS, CdSe/CuSe, CdSeTe, CdSeTe/CdS/ZnS, Mn:CdS, Cu:CdS, Cu:ZnS, Mn:ZnS, Mn:ZnSe, Cu:ZnSe, Tb:CdS or the Tb:ZnS.

3. SiO as claimed in claim 1 ₂The preparation method of the nano combined luminescent material of coated quantum dots, the size of wherein said quantum dot is in the scope of 1-10nm.

4. SiO as claimed in claim 1 ₂The preparation method of the nano combined luminescent material of coated quantum dots; Said organic reagent and hexanaphthene in the wherein said step 1 dissolve each other; Said organic reagent is hydrophobic, and said organic reagent is any one reagent or any mixture of plurality of reagents in normal hexane, toluene, YLENE, 4-Chlorotoluene 99.5, methylene dichloride, trichloromethane, tetrachloromethane and the sherwood oil reagent.

5. SiO as claimed in claim 1 ₂The preparation method of the nano combined luminescent material of coated quantum dots, the said tensio-active agent in the wherein said step 2 is any one tensio-active agent or any mixture of kinds of surface promoting agent among tensio-active agent NP5, NP9 and the Triton X-100.

6. SiO as claimed in claim 1 ₂The preparation method of the nano combined luminescent material of coated quantum dots, the said catalyzer in the wherein said step 2 is any one catalyzer or any multiple mixture of catalysts in catalyzer methylamine, ammoniacal liquor and the n n dimetylaniline.

7. SiO as claimed in claim 1 ₂The preparation method of the nano combined luminescent material of coated quantum dots, the said time (T1) in the wherein said step 3 is 20-80 hour.

8. SiO as claimed in claim 1 ₂The preparation method of the nano combined luminescent material of coated quantum dots, the said oil bath temperature (T) in the wherein said step 4 is 50-90 ℃, said soaking time (T2) is 0.5-2 hour.

9. SiO as claimed in claim 1 ₂The preparation method of the nano combined luminescent material of coated quantum dots, the said time (T3) in the wherein said step 6 is not less than 6 hours.