CN107119327B - Method for preparing large-area non-cracking colloidal photonic crystal film - Google Patents
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- CN107119327B CN107119327B CN201710225398.2A CN201710225398A CN107119327B CN 107119327 B CN107119327 B CN 107119327B CN 201710225398 A CN201710225398 A CN 201710225398A CN 107119327 B CN107119327 B CN 107119327B
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Abstract
The invention discloses a method for preparing a large-area non-cracking colloidal photonic crystal film, which comprises the following specific steps: dispersing the aqueous polyurethane emulsion into a colloidal particle solution; then, taking the prepared homogeneous solution as a coating solution, and coating a large-area colloidal photonic crystal film on a hydrophilic substrate by a wire rod in a blade mode; and spin-coating a layer of quantum dots on the surface of the colloidal photonic crystal film. The resonance effect of the colloidal photonic crystal in the visible light region can be utilized to obviously enhance the fluorescence signal of the quantum dot. The method overcomes the defect that the traditional colloidal photonic crystal film is easy to crack, has the advantages of simple operation, mild conditions, easy large-area construction and the like, and the prepared colloidal photonic crystal and quantum dot composite film has high fluorescence intensity and fluorescence stability and can provide ideas for rapidly preparing high-power QD-LED devices.
Description
Technical Field
The invention relates to a method for preparing a large-area non-cracking colloidal photonic crystal film, in particular to a method for realizing large-area film formation of photonic crystals without cracks by using hydrogen bonds in polyurethane to enhance the binding force between colloidal microspheres and further enhancing the fluorescence intensity of quantum dots.
Background
The colloidal photonic crystal is a novel functional material prepared from monodisperse organic or inorganic colloidal particles by a bottom-up method. The long-range ordered periodic arrangement in space has the characteristic of photon forbidden band, so that the method is widely applied to the fields of display, chemical sensing, fluorescence enhancement and the like. At present, how to solve the problem of large-area film formation without cracking becomes a hotspot of photonic crystal research. As methods for forming a film of a photonic crystal, there have been reported: the method comprises a vertical deposition method, an external field force induced assembly method, a template assembly method and the like, but the methods have the problems of complicated steps, high cost and the like, and the practical application of the colloidal photonic crystal is greatly limited. In addition, in the film forming process, when the solvent is volatilized, the capillary force between the colloidal microspheres can generate transverse compressive stress, when the transverse compressive stress exceeds a critical value, the finally formed photonic crystal film can generate cracks, and the large-area preparation of the colloidal photonic crystal film is severely limited by the generation of the cracks. Therefore, how to solve the cracking problem in the film forming process by using a simple, effective and low-cost method is very important for rapidly preparing the high-performance photonic crystal film on a large scale.
In recent years, although LED devices have experienced sufficient development, the lower light extraction efficiency severely limits the LED light source output power. Therefore, the development of high-power LED devices is becoming a key to widening the application field of LEDs.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects of complex film forming steps, easy cracking, difficult large-area construction and the like of the photonic crystal, thereby providing a method for preparing a large-area non-cracking colloidal photonic crystal film. The method has the characteristics of mild conditions, simple steps and good repeatability, and the prepared colloidal photonic crystal film has the characteristics of large area, no cracking and excellent optical properties.
In order to achieve the purpose, the technical scheme of the invention is to introduce the polyurethane emulsion containing the hydrogen bond network into a colloid microsphere emulsion system, and the bonding force between the microspheres is enhanced through the hydrogen bond action of the microspheres and the polyurethane network, so that the large-area film formation is realized without cracking. The invention utilizes the extremely strong Bragg diffraction effect of the photonic crystal film with high optical quality to make photons spread in the photonic crystal at a weakened group velocity, thereby achieving the effect of optical gain, namely the effect of fluorescence enhancement.
The specific technical scheme of the invention is as follows: a method for preparing a colloidal photonic crystal and quantum dot composite film comprises the following specific steps: dispersing the waterborne polyurethane into the colloidal particle solution; then, taking the prepared homogeneous solution as a coating solution, and coating a large-area colloidal photonic crystal film on a hydrophilic substrate by a wire rod in a blade mode; and finally, spin-coating a layer of quantum dots on the surface of the colloidal photonic crystal film by using a spin coating instrument.
Preferably, the coating liquid is a mixed aqueous solution of colloidal particles and polyurethane; wherein the mass concentration of the colloidal particles in the coating liquid is 25-35%, and the mass concentration of the polyurethane is 1-5%.
Preferably, the colloidal particles are monodisperse polystyrene colloidal microspheres with surface carboxyl modified; the particle size range of the surface carboxyl modified monodisperse polystyrene microsphere is 180nm-300nm, and the monodisperse coefficient is 1% -5%.
Preferably, the forbidden band position of the scraped colloidal photonic crystal film is between 510nm and 620 nm.
Preferably, the solution used for spin coating by a spin coater is a mixed aqueous solution of CdTe quantum dots and PVA, wherein the mass fraction of the CdTe quantum dots in the mixed aqueous solution is 0.1-1%, and the mass fraction of the PVA in the mixed aqueous solution is 0.5-2%.
Preferably, the emission peak of the CdTe quantum dots is between 510nm and 620 nm. The spin speed of the spin coater is preferably 1000rpm to 2500rpm for 30s to 60 s.
Preferably, the hydrophilic substrate is one of glass, silicon wafer or plastic. Preferably, the contact angle of the hydrophilic substrate is 10 ° to 25 °.
Has the advantages that:
1. the colloid photon crystal film prepared by the invention has the physical properties of flexibility, difficult cracking, gorgeous structural color and adjustable optical properties of forbidden band positions.
2. The colloidal photonic crystal film prepared by the invention has the characteristics of easy large-area construction and industrial application prospect.
3. The quantum dot film based on the colloidal photonic crystal prepared by the invention has excellent fluorescence performance and good stability, and the fluorescence intensity is obviously improved compared with that of the common quantum dot film.
4. The quantum dot film based on the colloidal photonic crystal prepared by the invention can be effectively applied to a light-emitting device as a phosphor.
Drawings
FIG. 1 is a diagram of a colloidal photonic crystal film according to example 1 of the present invention;
FIG. 2 is a scanning electron microscope image of the colloidal photonic crystal film according to example 1 of the present invention;
FIG. 3 is a reflection spectrum of a colloidal photonic crystal film according to example 1 of the present invention;
FIG. 4 is a fluorescence diagram of a colloidal photonic crystal enhanced quantum dot film according to example 1 of the present invention;
fig. 5 is a fluorescence spectrum of the quantum dot film under different substrates in example 1 of the present invention, in which a curve a is a fluorescence spectrum of the quantum dot with the non-cracked colloidal photonic crystal film as a background, b is a fluorescence spectrum of the quantum dot with the cracked colloidal photonic crystal film as a background, and c is a fluorescence spectrum of the quantum dot formed on the PET plastic.
Detailed Description
The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.
Example 1
Adding polyurethane emulsion into surface carboxyl modified monodisperse polystyrene microsphere emulsion with the particle size of 228nm and the monodisperse coefficient of 1% to prepare mixed solution, wherein the mass fraction of the polystyrene microspheres is 30%, and the mass fraction of the polyurethane is 1%. And (4) ultrasonically dispersing uniformly until no bubbles exist. Then, a filament rod is used for carrying out blade coating on the surface of the PET plastic film with the contact angle of 18 degrees, and after the solvent is dried, the photonic crystal film without cracking can be obtained.
FIG. 1 is a physical diagram of the photonic crystal film, the size of the photonic crystal film is 30 x 40cm, the photonic crystal film shows a bright green structural color, and the surface of the photonic crystal film is uniform and has no cracking phenomenon.
The photonic crystal film is subjected to electron microscope scanning, and the result is shown in figure 2, and the result shows that the prepared photonic crystal film consists of monodisperse colloidal particles which are closely arranged in a short-range order.
FIG. 3 is a reflection spectrum of the photonic crystal film, in which the photonic band gap of the photonic crystal film is 540nm, the half-peak width is 30nm, and the reflection intensity is high.
Adding water phase CdTe (emission peak 540nm) into PVA water solution to obtain mixed solution, wherein the mass fraction of CdTe in the mixed solution is 0.1%, and the mass fraction of PVA is 0.5%.
And dropwise adding a CdTe/PVA solution on the colloidal photonic crystal film with the forbidden band position of 540nm, and spin-coating at 1200rpm for 30 s.
And after the solvent is volatilized, carrying out solid fluorescence test on the quantum dot film enhanced by the colloidal photonic crystal.
FIG. 5 is a fluorescence spectrum of the non-cracking colloidal photonic crystal enhanced quantum dots. Wherein, curve a is the quantum dot fluorescence spectrum with the non-cracked colloidal photonic crystal film as the background, curve b is the quantum dot fluorescence spectrum with the cracked colloidal photonic crystal film as the background, and curve c is the quantum dot fluorescence spectrum of the film formed on the PET plastic. It can be seen that the fluorescence intensity of the CdTe quantum dots is increased by one time by the colloidal photonic crystal film without polyurethane, and the fluorescence intensity of the CdTe quantum dots is increased by three times by the colloidal photonic crystal film without cracking after the polyurethane is added. The fluorescence spectrum graph shows that the non-cracking colloidal photonic crystal film prepared by the invention has higher efficiency in the quantum dot fluorescence enhancement effect.
Example 2
The polyurethane emulsion is added into the surface carboxyl modified monodisperse polystyrene microsphere with the particle size of 211nm and the monodisperse coefficient of 3 percent to prepare a mixed solution, wherein the mass fraction of the polystyrene microsphere is 35 percent, and the mass fraction of the polyurethane is 3 percent. And (4) ultrasonically dispersing uniformly until no bubbles exist. Then, a glass surface with a contact angle of 13 degrees is subjected to blade coating by a silk rod, and after the solvent is dried, a photonic crystal film without cracking can be obtained.
Adding water phase CdTe (emission peak 500nm) into 1% PVA water solution to obtain mixed solution, wherein the mass fraction of CdTe in the mixed solution is 0.5%, and the mass fraction of PVA is 1%. And dropwise adding a CdTe/PVA solution on the colloidal photonic crystal film, and spin-coating at 1500rpm for 45 s.
The size of the prepared photonic crystal film is 35 x 42cm, the obtained colloidal photonic crystal film is subjected to reflection spectrum test, the forbidden band position is measured to be 500nm, the obtained photonic crystal/quantum dot composite film is subjected to fluorescence spectrum test, and the fluorescence emission peak is measured to be 502 nm. Compared with the original quantum dot film, the fluorescence intensity is greatly enhanced. The result shows that the photonic crystal film prepared by the invention has good fluorescence enhancement effect on the quantum dot film.
Example 3
Adding polyurethane emulsion into surface carboxyl modified monodisperse polystyrene microspheres with the particle size of 256nm and the monodisperse coefficient of 5% to prepare a mixed solution, wherein the mass fraction of the polystyrene microspheres is 25% and the mass fraction of polyurethane is 5%. And (4) ultrasonically dispersing uniformly until no bubbles exist. Then, a wire rod is used for blade coating on the surface of the silicon wafer with the contact angle of 24 degrees, and after the solvent is dried, the photonic crystal film without cracking can be obtained.
An aqueous phase CdTe (emission peak 610nm) was added to a 1.5% PVA aqueous solution to prepare a mixed solution. In the mixed solution, the mass fraction of CdTe is 1% and the mass fraction of PVA is 1.5%. And dropwise adding a CdTe/PVA solution on the colloidal photonic crystal film with the forbidden band position of 610nm, and spin-coating at the speed of 2000rpm for 60 s.
The size of the prepared photonic crystal film is 32 x 41cm, the obtained colloidal photonic crystal film is subjected to reflection spectrum test, the forbidden band position is measured to be 606nm, the obtained photonic crystal/quantum dot composite film is subjected to fluorescence spectrum test, and the fluorescence emission peak is measured to be 610 nm. Compared with the original quantum dot film, the fluorescence intensity is greatly enhanced. The result shows that the photonic crystal film prepared by the invention has good fluorescence enhancement effect on the quantum dot film.
Claims (4)
1. A method for preparing a large-area non-cracking colloidal photonic crystal film comprises the following specific steps: dispersing the waterborne polyurethane into the colloidal particle solution; then, taking the prepared homogeneous solution as a coating solution, and coating a colloidal photonic crystal film on a hydrophilic substrate by a wire rod in a scraping way; finally, spin-coating a layer of quantum dots on the surface of the colloidal photonic crystal film by using a spin coating instrument; wherein the coating liquid is a mixed aqueous solution of colloidal particles and polyurethane; wherein the mass concentration of the colloidal particles in the coating liquid is 25-35%, and the mass concentration of the polyurethane is 1-5%; the solution used by the spin coating of the spin coater is a mixed aqueous solution of CdTe quantum dots and PVA, wherein the mass fraction of the CdTe quantum dots in the mixed aqueous solution is 0.1-1%, and the mass fraction of the PVA in the mixed aqueous solution is 0.5-2%; the colloidal particles are monodisperse polystyrene colloidal microspheres with surface carboxyl modified; the particle size range of the surface carboxyl modified monodisperse polystyrene microsphere is 180nm-300nm, and the monodisperse coefficient is 1% -5%; the forbidden band position of the scraped colloidal photonic crystal film is between 510nm and 620 nm.
2. The process according to claim 1, characterized in that the emission peak of the CdTe quantum dots is between 510nm and 620 nm.
3. The method according to claim 1, wherein the spin speed of the spin coater is 1000rpm to 2500rpm for 30s to 60 s.
4. The method of claim 1, wherein the hydrophilic substrate is one of glass, silicon wafer, or plastic.
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US11541680B2 (en) | 2017-04-18 | 2023-01-03 | Korea Minting, Security Printing & Id Card Operating Corp. | Photonic crystal film, method for manufacturing same, and anti-forgery article comprising same |
| CN108099433A (en) * | 2017-12-19 | 2018-06-01 | 苏州中科纳福材料科技有限公司 | The preparation method of counter opal structure anti-counterfeiting transfer printing film |
| CN110042673B (en) * | 2019-04-28 | 2022-06-17 | 浙江理工大学 | Large-area rapid preparation method of photonic crystal structure color coating on surface of textile substrate |
| CN111826995B (en) * | 2020-01-20 | 2022-05-31 | 北京印刷学院 | Preparation method of high-brightness narrow-band-gap high-adhesion structural color film |
| CN111929991A (en) * | 2020-08-10 | 2020-11-13 | 大连理工大学 | Method for rapidly preparing colloidal photonic crystal array chip by utilizing laser direct writing |
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