A film material capable of exciting high-intensity circularly polarized light and a preparation method and application thereof

Abstract

The application discloses a film material capable of exciting high-intensity circularly polarized light and a preparation method and application thereof. The preparation method of the film material comprises the following steps: (1) uniformly stirring and mixing cellulose nanocrystal suspension and gelatin solution, and then drying into a film after ultrasonic treatment to obtain a cellulose nanocrystal / gelatin chiral film; (2) dispersing luminophores into water to obtain a luminophore solution; (3) placing the cellulose nanocrystal / gelatin chiral film at the bottom of a suction filter, then pouring the luminophore solution, and then performing suction filtration and vacuum drying to obtain the film material capable of exciting high-intensity circularly polarized light. The film material prepared in the application can produce high-intensity circularly polarized fluorescence, has good cyclic repeatability, and can be applied to asymmetric photosynthesis, encrypted transmission, biological imaging, anti-fake manufacturing, optical display and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional film material preparation, and particularly relates to a thin film material capable of exciting high-intensity circularly polarized light and a preparation method and application thereof. BACKGROUND

[0002] Chiral substances exist universally in nature, and the chiral structure is derived from the asymmetric state of internal molecules and molecular assemblies. Chiral molecules and molecular assemblies have peculiar chemical and optical activities. Circular dichroism is a representative chiral optical activity, which is caused by different absorption degrees of circularly polarized light with different rotation directions. Circularly polarized light is a special light, which can be obtained by superimposing two linearly polarized lights with equal frequencies, perpendicular vibration directions and a phase difference of (2n+1 / 2)π. Since circularly polarized light is the closest to natural light, and has potentials in many applications such as asymmetric photosynthesis, encryption transmission, biological imaging, anti-fake manufacturing and optical display, researchers have been trying to control the generation and propagation of circularly polarized light.

[0003] Finding chiral molecules to build chiral structures is an important channel to generate circularly polarized light. However, the building of chiral structures often requires complex chemical synthesis raw materials and tedious synthesis steps, which is not conducive to the precise control of circularly polarized light. At present, researchers try to use the principle of bionics to combine organic cholesteric chiral structure with luminophores to generate circularly polarized light, but there are still two difficulties: 1. The combination of cholesteric structure and luminophores mostly occurs in solution system, and the intensity of the generated circularly polarized light is not high; 2. Since the chiral structure and the luminophore are constant, the generated circularly polarized light cannot be controlled. These two points have been restricting the development of circularly polarized light in the field of optics. SUMMARY

[0004] The primary purpose of the present application is to overcome the shortcomings and deficiencies of the prior art, and to provide a preparation method of a thin film material capable of exciting high-intensity circularly polarized light.

[0005] Another purpose of the present application is to provide a thin film material capable of exciting high-intensity circularly polarized light prepared by the method.

[0006] Still another purpose of the present application is to provide the application of the thin film material capable of exciting high-intensity circularly polarized light.

[0007] The purposes of the present application are achieved by the following technical solutions:

[0008] A preparation method of a thin film material capable of exciting high-intensity circularly polarized light, comprising the following steps:

[0009] (1) stirring and mixing the cellulose nanocrystal suspension and the gelatin solution uniformly at 50±5℃, then treating by ultrasonic, to obtain a mixture; drying the mixture into a film to obtain the cellulose nanocrystal / gelatin chiral film;

[0010] (2) adding the luminophore into water, stirring and mixing uniformly to obtain a luminophore solution;

[0011] (3) placing the cellulose nanocrystal / gelatin chiral film at the bottom of a suction filter, then pouring the luminophore solution into the suction filter, and filtering by suction to obtain a wet luminophore / cellulose nanocrystal / gelatin chiral composite film (due to the effect of suction, the luminophore adheres to one side of the cellulose nanocrystal / gelatin chiral composite film); finally, vacuum drying to obtain the dried chiral composite film, which is the thin film material capable of exciting high-intensity circularly polarized light.

[0012] The size of the cellulose nanocrystal in the cellulose nanocrystal suspension in step (1) is 300-650 nm.

[0013] The cellulose nanocrystal in step (1) is prepared by mixing raw fibers with concentrated sulfuric acid, then heating and stirring at 45±5℃, followed by centrifugal washing and rotary evaporation concentration to obtain the cellulose nanocrystal.

[0014] The raw fibers are at least one of microcrystalline cellulose, coniferous wood fiber, broadleaf wood fiber, cotton fiber and bamboo fiber, etc.; preferably microcrystalline cellulose.

[0015] The solid-liquid ratio of the raw fibers to concentrated sulfuric acid is 1:5-15 g / ml; preferably 1:10 g / ml.

[0016] The concentration of the concentrated sulfuric acid is 64±2% by mass.

[0017] The heating and stirring reaction time is 40±5 min.

[0018] The concentration of the cellulose nanocrystal suspension in step (1) is 5-7% by mass; preferably 5% by mass.

[0019] The concentration of the gelatin solution in step (1) is 0.1-1% by mass; preferably 0.2-1% by mass; more preferably 0.6% by mass.

[0020] The mass ratio of the cellulose nanocrystal suspension to the gelatin solution in step (1) is (10-15):1.

[0021] The stirring and mixing conditions in step (1) are: stirring speed 600-1000 rpm (preferably 1000 rpm), and stirring time 10-15 min.

[0022] The ultrasonic treatment in step (1) is performed at an ultrasonic power of 30-45 kW (preferably 45 kW) for 0.5-2 min.

[0023] The drying and film-forming in step (1) is performed at a drying temperature of 20-35°C and a humidity of 50-60% to volatilize the solvent in the mixed solution to form a film; preferably, the drying and film-forming is performed at a drying temperature of 20-30°C and a humidity of 50%.

[0024] The cellulose nanocrystal / gelatin chiral film in step (1) has a water content of 5-7% by mass.

[0025] The cellulose nanocrystal / gelatin chiral film in step (1) has a thickness of 30-35 μm.

[0026] The luminophore in step (2) includes at least one of fluorescein thiocyanate, rare earth fluorescent substance, rhodamine 6G, lanthanide chelate, phosphor, oxadiazole and derivatives thereof; preferably, the luminophore is rhodamine 6G.

[0027] The luminophore solution in step (2) has a concentration of 0.2-1% by mass; preferably, the concentration is 0.2-0.8% by mass.

[0028] The stirring in step (2) is performed at 800-1200 rpm for 8-12 h; preferably, the stirring is performed at 1000 rpm for 10 h.

[0029] The suction filtration in step (3) is performed at a pressure of -0.04 to -0.06 MPa; preferably, the pressure is -0.05 to -0.06 MPa.

[0030] The vacuum drying in step (3) is performed at a drying temperature of 22-28°C and a vacuum degree of -0.05 to -0.8 MPa; preferably, the drying temperature is 25°C and the vacuum degree is -0.06 MPa.

[0031] The chiral composite film in step (3) has a thickness of 30-35 μm, because the luminophore has a low doping concentration of only 0.2-1 wt%, a small amount is added (e.g., 1-10 ml (preferably 3-5 ml) of luminophore solution is added to a cellulose nanocrystal / gelatin chiral film with a diameter of 35 mm and a thickness of 30-35 μm), and the size of the luminophore itself is extremely small, so that the content of the luminophore left in the film is small and does not affect the thickness of the final composite film, which still maintains a thickness of 30-35 μm.

[0032] A film material capable of exciting high-intensity circularly polarized light is prepared by any of the above methods.

[0033] The film material has the characteristics of exciting high-strength circularly polarized light, in particular, controllable high-strength circularly polarized light.

[0034] The film material capable of exciting high-strength circularly polarized light is applied in asymmetric photosynthesis, encrypted transmission, biological imaging, anti-counterfeiting manufacturing and / or optical display.

[0035] The present application has the following advantages and effects relative to the prior art:

[0036] (1) In the present application, gelatin is mixed into the cholesteric structure of cellulose nanocrystals by taking advantage of the characteristic that gelatin is insoluble in cold water. On the one hand, in the subsequent filtration process, if the pure cellulose nanocrystal (CNC) film is directly poured into a room-temperature luminophore aqueous solution, it is easy to disperse and the internal structure is destroyed. However, after adding gelatin, the cholesteric structure is firmly fixed by the gelatin and is not easy to be soaked by the room-temperature aqueous solution above and is not easy to be destroyed by the suction force below. Finally, a chiral film with high-strength circularly polarized light emission characteristics can be obtained. Although the functional film obtained by mixing gelatin and cellulose into a film usually has high-strength characteristics, such a film usually does not have the characteristics of cholesteric structure.

[0037] (2) In the present application, the luminophore is uniformly dispersed in the cellulose chiral film by filtration, and high-strength circularly polarized fluorescence can be generated. The present application has many advantages such as simple preparation process, low cost, controllable preparation, strong circularly polarized emission ability and good repeatability. In addition, the purpose of filtration in the present application is not to form a film, but to take advantage of the principle that the solution falls quickly. After the well-dispersed luminophore solution is poured on the film surface, it is quickly sucked away before it aggregates, so that the luminophore is uniformly dispersed on the film surface. In the conventional method in the art, the luminophore and cellulose are mixed and then self-assembled to form a luminophore cellulose film containing a cholesteric structure. The self-assembly time period is long, and in this process, the luminophore originally uniformly dispersed in the cellulose nanocrystal suspension will continuously aggregate. After a long self-assembly time, the luminophore is not uniformly dispersed in the same film, resulting in a large difference in fluorescence test results at different positions of the final sample. Therefore, in the present application, the luminophore and the cellulose-based cholesteric structure are combined by filtration to prepare a cellulose film material with uniform luminophore dispersion, which can generate high-strength circularly polarized light and controllable circularly polarized light.

[0038] (3) The cellulose raw material used to prepare the chiral film in the present application is green and environmentally friendly, and is a degradable product. It has certain economic and practicality for the preparation, use and recycling of products.

[0039] (4) The circularly polarized light performance of the chiral composite film material of the present application depends on the chiral structure of cellulose, so only the pitch of the chiral structure of cellulose needs to be changed to easily control the emission wavelength of the circularly polarized light, and the process is simple and easy to control.

[0040] (5) The chiral composite film prepared by the method of the present application has stronger circularly polarized light emission intensity than other organic small molecule materials (the thin film of the present application can produce an asymmetric factor of -5x10 -1 , and other organic small molecule materials generally have an asymmetric factor of 10 -2～-3 ), has better performance, is more flexible to control, has better cyclic repetition performance, and has the potential for commercial production value. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 Scanning electron microscope image of a local area of the chiral composite film prepared in Example 1.

[0042] Figure 2 Transmission spectrum of the chiral composite film prepared in Example 1.

[0043] Figure 3 Circularly polarized light spectrum of the chiral composite film prepared in Example 1 at the 5th repetition test. DETAILED DESCRIPTION

[0044] The present application will be further described in detail below with reference to examples, but the embodiments of the present application are not limited thereto. It should be noted that if the following processes are not specifically described in detail, they can be implemented or understood by those skilled in the art with reference to the prior art. If the reagents or instruments used are not marked with the manufacturer, they are considered to be conventional products that can be purchased on the market.

[0045] The size of the cellulose nanocrystals in the cellulose nanocrystal suspension in the present application is 300-650 nm (the solvent in the cellulose nanocrystal suspension is water), wherein the cellulose nanocrystals are prepared by a conventional sulfuric acid hydrolysis method, and the raw material is at least one of microcrystalline cellulose, coniferous wood fiber, broadleaf wood fiber, cotton fiber, and bamboo fiber; the specific preparation process is as follows: the raw fiber is mixed with 64% concentrated sulfuric acid at a ratio of 1 g (raw material) : 10 ml (64% concentrated sulfuric acid), heated and stirred at 45°C water temperature for 40 min, then washed by centrifugation and concentrated by rotary evaporation to prepare the desired cellulose nanocrystals. In the following examples, the raw material for preparing cellulose nanocrystals is microcrystalline cellulose, which can be obtained by conventional commercial methods.

[0046] Example 1

[0047] A thin film material capable of exciting high-intensity circularly polarized light and a preparation method thereof, comprising the following steps:

[0048] 1) 5wt% of cellulose nanocrystal suspension and 0.6wt% of gelatin solution (water was used as solvent, the same below) were mixed in the mass ratio of 10:1, the mixing condition was that the temperature was 50°C, the stirring speed was 1000rpm, and the stirring time was 10min, after mixing evenly, the final mixture was obtained by ultrasonic treatment for 0.5min under the condition of 45kW power;

[0049] 2) The mixture obtained in step 1) was placed in a cylindrical mold with a diameter of 35mm, and was dried into a film under the condition of a temperature of 20°C and a humidity of 50%, to obtain a cellulose nanocrystal / gelatin chiral film with a water content of 5wt% (thickness of 32μm);

[0050] 3) Rhodamine 6G was mixed with water (mixed in the concentration of 0.2wt% of Rhodamine 6G / water), and then was uniformly dispersed at room temperature (stirring for 10h at a stirring speed of 1000rpm) to obtain a luminophore solution;

[0051] 4) The cellulose nanocrystal / gelatin chiral film with a water content of 5wt% obtained in step 2) was placed at the bottom of a suction filter, 5ml of the luminophore solution obtained in step 3) was poured above the cellulose nanocrystal / gelatin chiral film, and a wet luminophore / cellulose nanocrystal / gelatin chiral composite film was obtained by suction filtration under the condition of a suction filtration pressure of-0.05MPa;

[0052] 5) The wet luminophore / cellulose nanocrystal / gelatin chiral composite film obtained in step 4) was placed in a vacuum drying oven for vacuum-assisted drying, and a dried chiral composite film (thickness of 32μm) was obtained after drying for about 5h under the condition of a drying temperature of 25°C and a vacuum degree of-0.06M.

[0053] The scanning electron microscope image of a local area of the chiral composite film prepared in this example is shown in Figure 1 From the figure, it can be seen that the chiral structure of the internal layered arrangement of the film is not damaged due to the incorporation of the luminophore and the pressure of the suction filtration device; the transmission spectrum is shown in Figure 2 The photonic band gap of the chiral composite film under the process condition is 550nm; the chiral composite film was subjected to circularly polarized fluorescence test (excitation wavelength of 350nm, repeated measurement for multiple times, and here only the results of the 5th repeated test are given), and the circularly polarized spectrum of the 5th repeated test is shown in Figure 3 From the figure, it can be seen that the film has a high circularly polarized fluorescence intensity, and the intensity is as high as-2350mdeg, and the asymmetry factor is-0.48; it is also confirmed that as long as the chiral structure of the film is not damaged, the film will maintain good repeated test results.

[0054] Example 2

[0055] A film material capable of exciting high-intensity circularly polarized light and a preparation method thereof, comprising the following steps:

[0056] 1) 5wt% of cellulose nanocrystal suspension and 1wt% of gelatin solution were mixed in a mass ratio of 15:1, the mixing conditions were: temperature 50°C, stirring speed 1000rpm, stirring time 15min, after uniform mixing, ultrasonic treatment was performed under the condition of power 45kW for 0.5min, and a final mixed solution was obtained;

[0057] 2) The mixed solution obtained in step 1) was placed in a cylindrical mold with a diameter of 35mm, and was dried into a film under the condition of temperature 20°C and humidity 50%, and a cellulose nanocrystal / gelatin chiral film with a water content of 6wt% (thickness 33μm) was obtained;

[0058] 3) Rhodamine 6G was mixed with water (mixed at a concentration of 0.4wt% of Rhodamine 6G / water), and then uniformly dispersed at room temperature (stirring speed 1000rpm, stirring time 10h), and a luminophore solution was obtained;

[0059] 4) The cellulose nanocrystal / gelatin chiral film with a water content of 5wt% obtained in step 2) was placed at the bottom of a suction filter, 4ml of the luminophore solution obtained in step 3) was poured onto the cellulose nanocrystal / gelatin chiral film, and suction filtration was performed under a suction filtration pressure of-0.05MPa, and a wet luminophore / cellulose nanocrystal / gelatin chiral composite film was obtained;

[0060] 5) The wet luminophore / cellulose nanocrystal / gelatin chiral composite film obtained in step 4) was placed in a vacuum drying oven, and dried under the condition of drying temperature 28°C and vacuum degree-0.06M for about 5h, and a dried chiral composite film (thickness 33μm) was obtained.

[0061] The circularly polarized fluorescence test result (excitation wavelength 350nm) of the chiral composite film prepared in this example when tested for the 5th time was as follows: the circularly polarized fluorescence test intensity of the chiral composite film was-2682mdeg, and the asymmetry factor was-0.50.

[0062] Example 3

[0063] A film material capable of exciting high-intensity circularly polarized light and a preparation method thereof, comprising the following steps:

[0064] 1) 6wt% of cellulose nanocrystal suspension and 0.4wt% of gelatin solution were mixed in a mass ratio of 12:1, the mixing conditions were: temperature 50°C, stirring speed 1000rpm, stirring time 10min, after uniform mixing, ultrasonic treatment was performed under the condition of power 45kW for 1min, and a final mixed solution was obtained;

[0065] 2) The mixture obtained in step 1) was placed in a cylindrical mold with a diameter of 35 mm and dried into a film under conditions of a temperature of 25°C and a humidity of 50%, to obtain a cellulose nanocrystal / gelatin chiral film with a water content of 7wt% (thickness of 34μm);

[0066] 3) Rhodamine 6G was mixed with water (mixed at a concentration of 0.6wt% of rhodamine 6G / water), and then uniformly dispersed at room temperature (stirred at a stirring speed of 1000 rpm for 10 h), to obtain a luminophore solution;

[0067] 4) The cellulose nanocrystal / gelatin chiral film with a water content of 5wt% obtained in step 2) was placed at the bottom of a suction filter, 3ml of the luminophore solution obtained in step 3) was poured above the cellulose nanocrystal / gelatin chiral film, and suction filtration was performed under a suction filtration pressure of -0.05 MPa, to obtain a wet luminophore / cellulose nanocrystal / gelatin chiral composite film;

[0068] 5) The wet luminophore / cellulose nanocrystal / gelatin chiral composite film obtained in step 4) was placed in a vacuum drying oven and dried under conditions of a drying temperature of 25°C and a vacuum degree of -0.08 M for about 5 h, to obtain a dried chiral composite film (thickness of 34μm).

[0069] The circularly polarized fluorescence test result (excitation wavelength of 350 nm) of the chiral composite film prepared in this example when tested for the 5th time was as follows: the circularly polarized fluorescence test intensity of the chiral composite film was -1979 mdeg, and the asymmetry factor was -0.36.

[0070] Example 4

[0071] A thin film material capable of exciting high-intensity circularly polarized light and a preparation method thereof, comprising the following steps:

[0072] 1) 5wt% of cellulose nanocrystal suspension was mixed with 0.5wt% of gelatin solution at a mass ratio of 11:1, the mixing conditions were: a temperature of 50°C, a stirring speed of 1000 rpm, and a stirring time of 10 min, after uniform mixing, ultrasonic treatment was performed under conditions of a power of 45 kW for 1.5 min, to obtain a final mixture;

[0073] 2) The mixture obtained in step 1) was placed in a cylindrical mold with a diameter of 35 mm and dried into a film under conditions of a temperature of 30°C and a humidity of 50%, to obtain a cellulose nanocrystal / gelatin chiral film with a water content of 6wt% (thickness of 33μm);

[0074] 3) Rhodamine 6G was mixed with water (mixed at a concentration of 0.8wt% of rhodamine 6G / water), and then uniformly dispersed at room temperature (stirred at a stirring speed of 1000 rpm for 10 h), to obtain a luminophore solution;

[0075] 4) The cellulose nanocrystal / gelatin chiral film with a water content of 5 wt% obtained in step 2) was placed at the bottom of a suction filter, and 3 ml of the luminophore solution obtained in step 3) was poured onto the cellulose nanocrystal / gelatin chiral film, and suction filtration was performed at a suction filtration pressure of -0.05 MPa, to obtain a wet luminophore / cellulose nanocrystal / gelatin chiral composite film;

[0076] 5) The wet luminophore / cellulose nanocrystal / gelatin chiral composite film obtained in step 4) was placed in a vacuum drying oven, and dried at a drying temperature of 22°C and a vacuum degree of -0.06 M for about 5 h, to obtain a dried chiral composite film (thickness: 33 pm).

[0077] The circularly polarized fluorescence test results (excitation wavelength: 350 nm) of the chiral composite film prepared in this example in the 5th repeated test were as follows: the circularly polarized fluorescence test intensity of the chiral composite film was -2763 mdeg, and the asymmetry factor was -0.51.

[0078] Example 5

[0079] A thin film material capable of exciting high-intensity circularly polarized light and a preparation method thereof, comprising the following steps:

[0080] 1) 7 wt% of a cellulose nanocrystal suspension was mixed with 0.2 wt% of a gelatin solution in a mass ratio of 10:1, the mixing conditions were as follows: a temperature of 50°C, a stirring speed of 1000 rpm, and a stirring time of 10 min, and after uniform mixing, ultrasonic treatment was performed under a power of 45 kW for 2 min, to obtain a final mixed solution;

[0081] 2) The mixed solution obtained in step 1) was placed in a cylindrical mold with a diameter of 35 mm, and dried into a film under conditions of a temperature of 20°C and a humidity of 50%, to obtain a cellulose nanocrystal / gelatin chiral film with a water content of 6 wt% (thickness: 31 pm);

[0082] 3) Rhodamine 6G was mixed with water (mixed at a concentration of 0.2 wt% of Rhodamine 6G / water), and then uniformly dispersed at room temperature (stirred at a stirring speed of 1000 rpm for 10 h), to obtain a luminophore solution;

[0083] 4) The cellulose nanocrystal / gelatin chiral film with a water content of 5 wt% obtained in step 2) was placed at the bottom of a suction filter, and 5 ml of the luminophore solution obtained in step 3) was poured onto the cellulose nanocrystal / gelatin chiral film, and suction filtration was performed at a suction filtration pressure of -0.06 MPa, to obtain a wet luminophore / cellulose nanocrystal / gelatin chiral composite film;

[0084] 5) The wet chiral composite film obtained in step 4) was placed in a vacuum drying oven and dried at a drying temperature of 25°C and a vacuum degree of -0.05M for about 5h to obtain a dried chiral composite film (thickness 31pm).

[0085] The circularly polarized fluorescence test results (excitation wavelength 350nm) of the chiral composite film prepared in this example in the 5th repeated test were as follows: the circularly polarized fluorescence test intensity of the chiral composite film was -1663mdeg, and the asymmetry factor was -0.33.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 4 is that no gelatin was added in step 1).

[0088] Result: After the pure cellulose nanocrystal film was placed in the suction filtration device, the cholesteric structure of the cellulose nanocrystal film was destroyed during the suction process due to the soaking of water from above and the large suction force from below, and no circularly polarized light could be generated.

[0089] Comparative Example 2

[0090] The difference between this comparative example and Example 4 is that the mixing method of the luminophore solution and the chiral film in step 4) is not suction filtration, but the chiral film is soaked in the luminophore solution for 1min, then taken out, and repeated 3 times.

[0091] Circularly polarized light tests were performed on the films prepared in Example 4 and this comparative example (excitation wavelength 350nm, both were the 5th repeated test results): under the same excitation conditions, the circularly polarized light intensity of Example 4 was -2763mdeg, and the circularly polarized light intensity of this comparative example was -1280mdeg.

[0092] Comparative Example 3

[0093] The difference between this comparative example and Example 4 is that no gelatin was added in step 1), and then the obtained cellulose nanocrystal suspension and luminophore (rhodamine) were added into water at the same time to disperse uniformly, and self-assembled into a film under the process conditions in Example 4.

[0094] The edge, sub-edge and center region of the same film in Comparative Example 3 were tested under the same conditions, and repeated three times. The results showed that the fluorescence intensities of the film edge, sub-edge and center region were 6x10 5 CPS, 5x10 3 CPS and 9x10 4 CPS, respectively, with a large difference in fluorescence intensity. The fluorescence intensities of the film edge, sub-edge and center region in Example 4 were all within the range of 5x10 5 CPS, with a small difference.

[0095] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A method for preparing a thin film material that can excite high intensity circularly polarized light, characterized by, The method comprises the following steps: (1) stirring and mixing the cellulose nanocrystal suspension and the gelatin solution uniformly at 50±5℃, and then treating with ultrasonic to obtain a mixed solution; drying the mixed solution into a film to obtain a cellulose nanocrystal / gelatin chiral film; (2) adding the luminophore into water and stirring and mixing uniformly to obtain a luminophore solution; (3) placing the cellulose nanocrystal / gelatin chiral film at the bottom of a suction filter, then pouring the luminophore solution into the suction filter, and then performing suction filtration to obtain a wet luminophore / cellulose nanocrystal / gelatin chiral composite film; and finally performing vacuum drying to obtain a dried chiral composite film, i.e. the film material capable of exciting high-intensity circularly polarized light.

2. The method according to claim 1, wherein the luminophore in step (2) comprises at least one of fluorescein thiocyanate, rare earth fluorescent substance, rhodamine 6G, lanthanide chelate, phosphorescent substance, and oxadiazole and derivatives thereof.

3. The method according to claim 2, wherein the luminophore in step (2) is rhodamine 6G.

4. The method according to claim 1, wherein the concentration of the cellulose nanocrystal suspension in step (1) is 5-7% by mass; the concentration of the gelatin solution in step (1) is 0.1-1% by mass; the mass ratio of the cellulose nanocrystal suspension to the gelatin solution in step (1) is 10-15:1; the concentration of the luminophore solution in step (2) is 0.2-1% by mass.

5. The method according to claim 4, wherein the concentration of the cellulose nanocrystal suspension in step (1) is 5% by mass; the concentration of the gelatin solution in step (1) is 0.2-1% by mass; the concentration of the luminophore solution in step (2) is 0.2-0.8% by mass.

6. The method according to claim 1, wherein the water content of the cellulose nanocrystal / gelatin chiral film in step (1) is 5-7% by mass; the thickness of the cellulose nanocrystal / gelatin chiral film in step (1) is 30-35 μm; the thickness of the chiral composite film in step (3) is 30-35 μm.

7. The method according to claim 1, wherein the size of the cellulose nanocrystal in the cellulose nanocrystal suspension in step (1) is 300-650 nm.

8. The method according to claim 1, wherein the stirring and mixing in step (1) is performed at a stirring speed of 600-1000 rpm for 10-15 min. ​ ​ ​ ​ ​ ​ ​ The ultrasonic treatment in step (1) is performed at an ultrasonic power of 30-45 kW for 0.5-2 min. The drying and film forming in step (1) is performed at a drying temperature of 20-35℃ and a humidity of 50-60%. The stirring in step (2) is performed at 800-1200 rpm for 8-12 h. The suction filtration in step (3) is performed at a pressure of -0.04 to -0.06 MPa. The vacuum drying in step (3) is performed at a drying temperature of 22-28℃ and a vacuum degree of -0.05 to -0.8 MPa.

9. A thin film material that can excite high intensity circularly polarized light, characterized in that: Prepared by the method of any one of claims 1-8.

10. Use of the thin film material capable of exciting high intensity circularly polarized light according to claim 9 in asymmetric photosynthesis, encrypted transmission, biological imaging, anti-counterfeiting manufacturing and / or optical display.

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