阅读说明：本技术 一种ZnO量子点掺杂的SiO2下转换减反射膜及其制备方法 (ZnO quantum dot doped SiO2Down-conversion antireflection film and preparation method thereof ) 是由 黄建勇 费广涛 许少辉 张敏 倪志龙 王彪 于 2020-10-30 设计创作，主要内容包括：本发明涉及一种ZnO量子点掺杂的SiO-2下转换减反射膜及其制备方法。所述制备方法包括制备ZnO量子点、制备酸性SiO-2溶胶、掺入ZnO量子点、提拉镀膜、高温退火。本发明将ZnO量子点离心、清洗可以去除残余的离子和未反应的杂质,然后在不烘干的情况下掺杂在酸性SiO-2溶胶中,可以得到均匀分散的溶胶,通过提拉镀膜制备出下转化减反射膜,该薄膜既具有减反功能,又可以将紫外光转化为可见光,且量子点退火未出现荧光淬灭。本发明的制备方法操作简单且工艺成熟,成本更低,ZnO发射波长可调,可以通过控制ZnO量子点的粒径改变发射峰的位置。有望通过光催化减少表面污渍,应用到光伏系统,农业薄膜领域。(The invention relates to ZnO quantum dot doped SiO 2 A down-conversion antireflection film and a method for manufacturing the same. The preparation method comprises the steps of preparing ZnO quantum dots and preparing acidic SiO 2 Sol, doping ZnO quantum dots, pulling and coating, and high-temperature annealing. The ZnO quantum dots are centrifuged and cleaned to remove residual ions and unreacted impurities, and then are doped in acidic SiO under the condition of no drying 2 Uniformly dispersed sol can be obtained in the sol, a down-conversion antireflection film is prepared by lifting and coating, the film has an antireflection function, ultraviolet light can be converted into visible light, and fluorescence quenching does not occur during quantum dot annealing. The preparation method of the inventionThe preparation method is simple, the process is mature, the cost is lower, the ZnO emission wavelength can be adjusted, and the position of an emission peak can be changed by controlling the particle size of the ZnO quantum dot. Is expected to reduce surface stains through photocatalysis, and is applied to the fields of photovoltaic systems and agricultural films.)

1. ZnO quantum dot doped SiO₂The preparation method of the down-conversion antireflection film is characterized by comprising the following steps of:

s1, preparing ZnO quantum dots: preparing ZnO quantum dots by a sol-gel method;

s2 preparation of acidic SiO₂Sol: tetraethyl orthosilicate TEOS (TEOS) is used as a silicon source, nitric acid is used as a catalyst, absolute ethyl alcohol is used as a solvent, and the acidic SiO is prepared by hydrolytic polymerization reaction₂Sol;

s3, doping ZnO quantum dots: dispersing ZnO quantum dots in absolute ethyl alcohol to obtain ZnO quantum dotsThe dispersion concentration of the dots is 0.5-3 mol/L, and then the acidic SiO after aging for 3 days₂The sol is added into absolute ethyl alcohol solution dispersed with ZnO quantum dots drop by drop, and the dropwise added acidic SiO is stirred while being dropwise added₂SiO contained in the sol₂The mol ratio of the ZnO to ZnO contained in the ZnO quantum dots is 1 (2-8), and the ZnO quantum dots are stirred for 5-10 min to prepare sol doped with the ZnO quantum dots;

s4, pulling and coating: carrying out pulling coating on the cleaned glass substrate in the ZnO quantum dot doped sol, wherein the descending speed of the glass substrate is 50-100 mm/min, the dipping time of the glass substrate in the sol is 60s, the ascending speed of the glass substrate is 50-100 mm/min, and drying the coated glass substrate in a 60 ℃ oven;

s5, high-temperature annealing: putting the dried coated glass substrate into a tube furnace, annealing for 2-3 h at 500 ℃, naturally cooling to room temperature in the tube furnace, and taking out to obtain the ZnO quantum dot doped SiO₂A down-conversion anti-reflective film;

wherein, the steps S1 and S2 are not in sequence.

2. The ZnO quantum dot doped SiO of claim 1₂The preparation method of the down-conversion antireflection film is characterized in that the preparation method of the ZnO quantum dots in the step S1 is as follows:

weighing zinc acetate dihydrate Zn (AC)₂·2H₂Dissolving O in the absolute ethyl alcohol solution, stirring in a water bath at the temperature of 30-80 ℃ for 30-100 min, and marking as solution A;

weighing potassium hydroxide, dissolving in absolute ethyl alcohol, stirring until the potassium hydroxide is dissolved, and marking as a solution B;

then dropwise adding the solution B into the solution A, wherein the solution A contains Zn (AC)₂·2H₂The molar mass ratio of KOH in the O solution to the B solution is 1:1.5, and stirring is carried out in a water bath at the temperature of 30-80 ℃ for 30-60 min to obtain a clear solution;

and mixing n-hexane with the clarified solution according to a volume ratio of 3:1, standing for 20min, centrifuging, and washing to obtain the ZnO quantum dots.

3. The method of claim 1ZnO quantum dot doped SiO₂The method for producing a down-conversion antireflection film, characterized in that the acidic SiO in step S2₂The preparation method of the sol comprises the following steps:

tetraethyl orthosilicate (TEOS) and absolute ethyl alcohol are mixed, and are magnetically stirred for 20-30 min at room temperature at the rotating speed of 500-600 r/min to prepare a solution C;

adding HNO₃And H₂Mixing and stirring the mixture O for 2-3 min to prepare a solution D;

wherein, TEOS, absolute ethyl alcohol and HNO in the solutions C and D₃、H₂The molar ratio of the O substances is 1:7:0.035: 4;

slowly dripping the solution D into the solution C to prepare a reaction precursor solution;

placing the prepared reaction precursor solution into a constant-temperature water bath kettle at 60 ℃, magnetically stirring at the rotating speed of 500-600 r/min, and reacting for 2-5 h to obtain the acidic SiO₂And (3) sol.

4. The ZnO quantum dot doped SiO of claim 1₂The method for producing a down-conversion antireflection film is characterized in that the cleaning step of the glass substrate in step S4 is as follows: soaking the glass substrate in 5 wt% sodium hydroxide solution for 20-30 min, wiping the glass substrate clean, washing with clear water or absolute ethyl alcohol for 3-5 times, soaking in deionized water, performing ultrasonic treatment for 20min, and drying in an oven for later use.

5. ZnO quantum dot doped SiO prepared by the preparation method of any one of claims 1 to 4₂Down-converting the antireflection film.

Technical Field

The invention belongs to the field of nano materials, relates to a nano film preparation technology with down-conversion and antireflection dual functions, and particularly relates to acidic SiO-based ZnO quantum dot doping₂A down-conversion antireflection film prepared by sol and a preparation method thereof.

Background

At present, the maximum photoelectric conversion efficiency of the crystalline silicon solar cell reaches 24.7%, and in order to further improve the photoelectric conversion efficiency of the crystalline silicon solar cell, the following two aspects are generally considered: 1. Plating an anti-reflection film material on the cover plate, and reducing the reflection of the solar cell cover plate to incident light as much as possible so as to increase the utilization of the solar cell to light; 2. and adding conversion materials and down-conversion materials to convert light outside the response waveband of the solar cell into light of the waveband which can be effectively responded by the solar cell to the greatest extent. The band range of the solar spectrum of the radiation reaching the ground is about 295-2500 nm, and the band of the effective response of the crystalline silicon solar cell is 400-1100 nm. By adding the conversion material and the down-conversion material, light with the wavelength less than 400nm and light with the wavelength more than 1100nm can be effectively converted into light with the wave band of 400-1100 nm theoretically. In order to reduce the reflection of light from the surface of the solar cell, better antireflection film materials have been developed, such as: mazur et al alternately deposit TiO by microwave-assisted magnetron sputtering₂/SiO₂A five-layer antireflection film having a transmittance in the visible light band of 97% or more (Applied Surface Science, 2016, 380, 165). Song et al prepared TiO by dip-coating method₂ /SiO₂Double-layer dense antireflection film with a photovoltaic weighted average transmittance of 94.5% (Optik. International Journal for Light and Electron Optics, 2013, 124(18), 3392.) although antireflection films can reduce Light reflection wellLight outside the 400-1100 nm wavelength band cannot be effectively used. To solve this problem, one can convert ultraviolet light into visible or near-infrared light by tuning the spectrum by doping the antireflective film with a rare earth. For example: eu is doped in porous silicon dioxide antireflection film layer by sol-gel method³⁺Ion, Eu³⁺Ions can absorb purple light and ultraviolet light with the wavelength of 393nm and emit red light with the wavelength of 612nm (the influence of rare earth europium doped porous silicon dioxide antireflection film on the efficiency of a solar cell, Chengmjun and the like, functional materials and devices, 2009, volume 15, No. 3, page 295). Doping rare earth Tb in silicon dioxide antireflection film by sol-gel method of Chen Wujun et al³⁺Ion, Tb³⁺The ions can absorb light with the wavelength of 310-322 nm and 330-380 nm and emit green light with the wavelength of about 544nm (a rare earth terbium-doped silicon dioxide antireflection and light wave conversion film for a solar cell, Chen Wu Jun, 2016, school news of northwest university, volume 46, phase 1, page 28). However, rare earth materials are expensive and not suitable for mass production.

Disclosure of Invention

The invention aims to overcome the defects of high preparation cost and low efficiency of an antireflection film in the prior art and provides SiO doped with ZnO quantum dots₂A method of making a down-conversion antireflection film.

In order to overcome the defects in the prior art, the invention provides the SiO doped with the ZnO quantum dots₂Down-converting the antireflection film.

In order to solve the technical problem of the invention, the technical scheme adopted is SiO doped with ZnO quantum dots₂The preparation method of the down-conversion antireflection film comprises the following steps:

s1, preparing ZnO quantum dots: preparing ZnO quantum dots by a sol-gel method;

s2 preparation of acidic SiO₂Sol: tetraethyl orthosilicate TEOS (TEOS) is used as a silicon source, nitric acid is used as a catalyst, absolute ethyl alcohol is used as a solvent, and the acidic SiO is prepared by hydrolytic polymerization reaction₂Sol;

s3, doping ZnO quantum dots: dispersing ZnO quantum dots in absolute ethyl alcohol, wherein the dispersion concentration of the ZnO quantum dots is 0.5-3 mol/L, and aging for 3 days to obtain acidic SiO₂The sol is added into absolute ethyl alcohol solution dispersed with ZnO quantum dots drop by drop, and the dropwise added acidic SiO is stirred while being dropwise added₂SiO contained in the sol₂The mol ratio of the ZnO to ZnO contained in the ZnO quantum dots is 1 (2-8), and the ZnO quantum dots are stirred for 5-10 min to prepare sol doped with the ZnO quantum dots;

s4, pulling and coating: carrying out pulling coating on the cleaned glass substrate in the ZnO quantum dot-doped sol, wherein the descending speed of the glass substrate is 50-100 mm/min, the dipping time of the glass substrate in the sol is 60s, the ascending speed of the glass substrate is 50-100 mm/min, and drying the coated glass substrate in a drying oven at 60 ℃;

s5, high-temperature annealing: putting the dried coated glass substrate into a tube furnace, annealing for 2-3 h at 500 ℃, naturally cooling to room temperature in the tube furnace, and taking out to obtain the ZnO quantum dot doped SiO₂A down-conversion anti-reflective film;

wherein, the steps S1 and S2 are not in sequence.

SiO doped as the ZnO quantum dot₂The preparation method of the down-conversion antireflection film is further improved:

preferably, the preparation method of the ZnO quantum dots in step S1 is as follows:

weighing zinc acetate dihydrate Zn (AC)₂·2H₂Dissolving O in the absolute ethyl alcohol solution, stirring in a water bath at the temperature of 30-80 ℃ for 30-100 min, and marking as A solution;

weighing potassium hydroxide, dissolving in absolute ethyl alcohol, stirring until the potassium hydroxide is dissolved, and marking as a solution B;

then dropwise adding the solution B into the solution A, wherein the solution A contains Zn (AC)₂·2H₂The molar mass ratio of KOH in the O solution to the B solution is 1:1.5, and stirring is carried out in a water bath at the temperature of 30-80 ℃ for 30-60 min to obtain a clear solution;

and mixing n-hexane with the clarified solution according to a volume ratio of 3:1, standing for 20min, centrifuging, and washing to obtain the ZnO quantum dots.

Preferably, the acidic SiO in step S2₂The preparation method of the sol comprises the following steps:

tetraethyl orthosilicate (TEOS) and absolute ethyl alcohol are mixed, and are magnetically stirred for 20-30 min at room temperature at the rotating speed of 500-600 r/min to prepare a solution C;

adding HNO₃And H₂Mixing and stirring the mixture O for 2-3 min to prepare a solution D;

wherein, TEOS, absolute ethyl alcohol and HNO in the solutions C and D₃、H₂The molar ratio of the O substances is 1:7:0.035: 4;

slowly dripping the solution D into the solution C to prepare a reaction precursor solution;

placing the prepared reaction precursor solution into a constant-temperature water bath kettle at 60 ℃, magnetically stirring at the rotating speed of 500-600 r/min, and reacting for 2-5 h to obtain the acidic SiO₂And (3) sol.

Preferably, the cleaning step of the glass substrate in step S4 is as follows: soaking the glass substrate in 5 wt% sodium hydroxide solution for 20-30 min, wiping the glass substrate clean, washing with clear water or absolute ethyl alcohol for 3-5 times, soaking in deionized water for 20min by ultrasound, and finally drying in an oven for later use.

In order to solve another technical problem of the invention, the technical scheme is that the ZnO quantum dot doped SiO prepared by any one of the preparation methods₂Down-converting the antireflection film.

Compared with the prior art, the invention has the beneficial effects that:

(1) doping ZnO quantum dots to SiO in the prior art₂The following problems generally exist in sols:

1) ZnO quantum dots and acidic SiO₂The direct mixing of the sol can cause the phenomenon of fluorescence quenching, and can also introduce K⁺、Zn²⁺Plasma, the refractive index can be reduced after film coating; 2) ZnO quantum dots and alkaline SiO₂Directly mixing the sol, and standing the sol for gelation; 3) drying the centrifuged ZnO quantum dots and adding the dried ZnO quantum dots to acid or alkaline SiO₂In the sol, ZnO quantum dots can not be dissolved and dispersed and can be precipitated at the bottom,a uniformly dispersed sol cannot be obtained; 4) quantum dots are inherently unstable and fluorescence quenching may occur after annealing. The ZnO quantum dots are centrifuged and cleaned to remove residual ions and unreacted impurities, and then are doped in acidic SiO under the condition of no drying₂Uniformly dispersed sol can be obtained in the sol, a down-conversion antireflection film is prepared by lifting and coating, the film has an antireflection function, ultraviolet light can be converted into visible light, and fluorescence quenching does not occur during quantum dot annealing.

(2) The sol-gel technology adopted by the invention is simple to operate and mature in process. The ZnO quantum dots are used for replacing rare earth as the luminescent centers, so that the manufacturing cost is lower; compared with rare earth, the ZnO quantum dots can be effectively excited by ultraviolet light smaller than 380nm to emit visible light of 500-600 nm, down-conversion of light is achieved, the specific waveband range is determined according to the particle size of the ZnO quantum dots, and the position of an emission peak can be changed by controlling the particle size of the ZnO quantum dots.

(3) And as ZnO nano materials are often used as photocatalysts, the down-conversion antireflection film prepared by the preparation method disclosed by the invention is expected to reduce surface stains through photocatalysis, and can be applied to the fields of photovoltaic systems and agricultural films.

Drawings

FIG. 1(a) is SiO without doped ZnO quantum dots₂An electron microscope image of the thin film, and fig. 1(b) is an electron microscope image of the thin film doped with ZnO quantum dots prepared in example 1;

FIG. 2 is a digital photograph of a down-conversion antireflection film prepared in example 1 of the present invention irradiated with a 365nm violet lamp;

FIG. 3 is a graph of the transmittance of pure glass, ZnO quantum dot doped anti-reflection film samples 1 and 2 prepared in examples 1 and 2;

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments, and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort belong to the protection scope of the present invention.

Example 1

S1, preparation of ZnO quantum dots: and preparing the ZnO quantum dots by adopting a sol-gel method. First, 2.4g of Zn (AC)₂·2H₂Dissolving O in 40ml of absolute ethanol solution, stirring in water bath at 30 ℃ for 30min, and recording as A solution. 0.9g of potassium hydroxide is simultaneously weighed and dissolved in 20ml of absolute ethyl alcohol, and the solution is marked as solution B after being stirred until being dissolved. And dropwise adding the solution B into the solution A, and stirring in a water bath at 30 ℃ for 30min to obtain a clear solution. And mixing n-hexane with the clear solution according to the volume ratio of 3:1, standing for 20min, centrifuging, and washing to obtain ZnO quantum dots for later use.

S2, acidic SiO₂Preparing sol: firstly, weighing 15ml of TEOS and 28ml of absolute ethyl alcohol, mixing, and magnetically stirring for 20min at room temperature at the rotating speed of 600r/min to prepare a solution C. Take 110uml HNO₃And 5ml of H₂And mixing and stirring the mixture O for 2-3 min to prepare a solution D. Slowly dripping the solution D into the solution C to form a reaction precursor solution, putting the prepared precursor solution into a constant-temperature water bath kettle, setting the water temperature to be 60 ℃, performing magnetic stirring at the rotating speed of 600r/min, and reacting for 3 hours to obtain the acidic SiO₂And (3) sol. Acidic SiO₂Aging the sol at room temperature for 3 days for later use;

s3, doping of ZnO quantum dots: firstly, 0.62g of ZnO quantum dots which are centrifuged out are dispersed in 5ml of absolute ethyl alcohol, and then 30ml of SiO which is aged for 3 days is taken₂Dropwise adding the sol into an absolute ethyl alcohol solution dispersed with ZnO quantum dots under the condition of magnetic stirring, and stirring for 5 min;

s4, pulling and coating: and (2) carrying out pulling coating on the cleaned glass substrate in the ZnO quantum dot doped sol, wherein the descending speed of the glass substrate is 100mm/min during pulling coating, the dipping time of the glass substrate in the sol is 60s, the ascending speed of the glass substrate is 100mm/min, and drying the coated glass substrate in a drying oven at the temperature of 60 ℃.

S5, high-temperature annealing: putting the dried coated glass substrate into a tube furnace, annealing for 2h at 500 ℃, naturally cooling to room temperature in the tube furnace, and taking out to prepare SiO doped with ZnO quantum dots₂Film(s)1。

Example 2

Example 2 preparation of ZnO Quantum dot doped SiO₂Method for down-converting antireflection film referring to example 1, except for adding dropwise aged acidic SiO in step S3₂The volume of the sol is 10ml, and the specific steps are as follows:

s1, preparation of ZnO quantum dots: and preparing the ZnO quantum dots by adopting a sol-gel method. First, 2.4g of Zn (AC)₂·2H₂Dissolving O in 40ml absolute ethanol (absolute ethanol) solution, stirring in water bath at 30 deg.C for 30min, and recording as A solution. 0.9g of potassium hydroxide is simultaneously weighed and dissolved in 20ml of absolute ethyl alcohol, and the solution is marked as solution B after being stirred until being dissolved. And dropwise adding the solution B into the solution A, and stirring in a water bath at 30 ℃ for 30min to obtain a clear solution. Mixing n-hexane with the clarified solution according to a volume ratio of 3:1, standing for 20min, centrifuging, and washing to obtain ZnO quantum dots for later use;

s2, acidic SiO₂Preparing sol: firstly, weighing 15ml of TEOS and 28ml of absolute ethyl alcohol, mixing, and magnetically stirring for 20min at room temperature at the rotating speed of 600r/min to prepare a solution C. Take 110uml HNO₃And 5ml of H₂And mixing and stirring the mixture O for 2-3 min to prepare a solution D. Slowly dripping the solution D into the solution C to form a reaction precursor solution, putting the prepared precursor solution into a constant-temperature water bath kettle, setting the water temperature to be 60 ℃, performing magnetic stirring at the rotating speed of 600r/min, and reacting for 3 hours to obtain the acidic SiO₂Sol of acidic SiO₂Aging the sol at room temperature for 3 days for later use;

s3, doping of ZnO quantum dots: firstly, 0.62g of ZnO quantum dots which are centrifuged out are dispersed in 5ml of absolute ethyl alcohol, and then 10ml of acidic SiO which is aged for 3 days is taken₂Dropwise adding the sol into an absolute ethyl alcohol solution dispersed with ZnO quantum dots under the condition of magnetic stirring, and stirring for 5 min;

s4, pulling and coating: carrying out pulling coating on the cleaned glass substrate in the ZnO quantum dot doped sol, wherein the descending speed of the glass substrate is 100mm/min, the dipping time of the glass substrate in the sol is 60s, the ascending speed of the glass substrate is 100mm/min, and the coated glass substrate is dried in a drying oven at the temperature of 60 ℃;

s5, high-temperature annealing: putting the dried coated glass substrate into a tube furnace, annealing for 2h at 500 ℃, naturally cooling to room temperature in the tube furnace, and taking out to prepare SiO doped with ZnO quantum dots₂A film 2.

Comparative example

S1, acidic SiO₂Preparing sol: firstly, weighing 15ml of TEOS and 28ml of absolute ethyl alcohol, mixing, and magnetically stirring for 20min at room temperature at the rotating speed of 600r/min to prepare a solution C; take 110uml HNO₃And 5ml of H₂Mixing and stirring the mixture O for 2-3 min to prepare a solution D; slowly dripping the solution D into the solution C to form a reaction precursor solution, putting the prepared precursor solution into a constant-temperature water bath kettle, setting the water temperature to be 60 ℃, performing magnetic stirring at the rotating speed of 600r/min, and reacting for 3 hours to obtain the acidic SiO₂Sol of acidic SiO₂Aging the sol at room temperature for 3 days for later use;

s2, doping of ZnO quantum dots: firstly, 0.62g of ZnO quantum dots which are centrifuged out are dispersed in 5ml of absolute ethyl alcohol, and then 10ml of acidic SiO which is aged for 3 days is taken₂And dropwise adding the sol into an absolute ethyl alcohol solution dispersed with ZnO quantum dots under the condition of magnetic stirring, and stirring for 5 min.

S3, pulling and coating: carrying out pulling coating on the cleaned glass substrate in the ZnO quantum dot doped sol, wherein the descending speed of the glass substrate is 100mm/min, the dipping time of the glass substrate in the sol is 60s, the ascending speed of the glass substrate is 100mm/min, and the coated glass substrate is dried in a drying oven at the temperature of 60 ℃;

s4, high-temperature annealing: putting the dried coated glass substrate into a tube furnace, annealing for 2h at 500 ℃, naturally cooling to room temperature in the tube furnace, and taking out to prepare SiO without doping ZnO quantum dots₂A film.

SiO prepared by the comparative example and not doped with ZnO quantum dots₂The thin film and the ZnO quantum dot doped thin film 1 prepared in example 1 were respectively subjected to scanning electron microscopy, and the results are respectively shown in fig. 1(a) and (b). The undoped ZnO quantum can be visually seen by scanning picturesThe thin film of dots still has acidic SiO₂The dense network structure of the film, but the surface of the film doped with ZnO quantum dots is rougher, and the existence of some small particles can be seen, and the small particles are ZnO quantum dots.

SiO of ZnO quantum dot doped prepared in example 1₂The film 2 takes digital photos under 365nm ultraviolet lamp irradiation, as shown in fig. 2, fig. 2(a) is a color picture for conveniently and visually seeing the color, and fig. 2 (b) is a black and white picture; as can be seen from FIG. 2, the film emits yellow light, and the conversion of purple light or ultraviolet light into yellow light can be visually seen, which further proves that the ZnO quantum dots exist and are not damaged by annealing.

Pure glass, SiO doped with ZnO quantum dots prepared in examples 1 and 2 respectively₂The films 1 and 2 were tested for their transmittance at different wavelengths, and the results are shown in FIG. 3; as can be seen from fig. 3, the ZnO quantum dot doped anti-reflection film plated on glass prepared by the preparation method of the present invention has higher transmittance than pure glass; and the preparation method is doped with acidic SiO₂The more the amount of sol is, the higher the transmittance of the antireflection film produced.

It should be understood by those skilled in the art that the foregoing is only illustrative of several specific embodiments of the invention, and is not exhaustive of the invention. It should be noted that many variations and modifications are possible to those skilled in the art, and all variations and modifications that do not depart from the scope of the invention as set forth in the claims should be deemed to be a part of the disclosure.