Solid cholesteric liquid crystal with multi-step circular polarization luminescence inversion, preparation method and application of solid cholesteric liquid crystal

Abstract

The invention discloses a solid cholesteric liquid crystal with multi-step circular polarization luminescence inversion, a preparation method and application thereof. The small organic molecules and the chiral luminescent molecules are assembled together in a thermal annealing process to form a solid cholesteric liquid crystal with a circularly polarized luminescent property; according to the invention, a high-temperature cholesteric liquid crystal construction element is used as a host molecule, a chiral luminescent molecule is used as a guest molecule, and the construction of the panchromatic circularly polarized luminescent liquid crystal material is realized by regulating and controlling the luminescent color and concentration of the chiral luminescent molecule; the liquid crystal material realizes inversion of a multi-step circular polarization light-emitting signal by accurately regulating and controlling the concentration of chiral light-emitting molecules, and shows a remarkable light-emitting asymmetry factor. The material has excellent circular polarization luminescence performance, and lays a solid foundation for application in the field of advanced information encryption. The preparation method of the material is simple and convenient to operate and suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to circularly polarized luminescent materials, preparation methods and applications, and in particular to a solid-state cholesteric liquid crystal with multi-step circularly polarized luminescent inversion, a preparation method and applications. Background Art

[0002] Circularly polarized luminescent (CPL) materials not only have the ability to dynamically regulate the emission wavelength and luminescence intensity of ordinary luminescent materials, but also have complex chiral dimension information regulation characteristics. This unique property makes CPL materials have important potential application value in the fields of information encryption, anti-counterfeiting technology, chiral sensing and asymmetric synthesis. In recent years, cholesteric liquid crystals (CLCs) have stood out in the field of CPL materials due to their unique self-organized spiral superstructure and ability to respond to external stimuli. CLCs can generate materials with significant luminescence asymmetry factors (g lum ) has become an ideal candidate material in this field. When constructing liquid crystal materials with CPL properties, it is crucial to select appropriate chiral inducers and determine the appropriate concentration compatible with the liquid crystal system. In theory, by gradually adjusting the concentration of chiral emitters in CLCs, the photonic band gap (PBG) position and the emission spectrum can be gradually matched and then separated, thereby optimizing the helical superstructure and achieving precise control of the CPL characteristics. However, excessively high chiral inducer concentrations may lead to phase separation problems, limiting the realization of multi-step CPL inversion. In addition, given that the mobility of traditional liquid crystal materials limits their practical application range, it is particularly critical to develop solid-state CLCs to achieve multi-step CPL inversion. Therefore, constructing solid-state CLCs with multi-step CPL inversion capabilities will not only overcome the application limitations of liquid crystal materials, but will also lay the foundation for their wide application in multiple advanced technology fields. Summary of the invention

[0003] Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a solid-state cholesteric liquid crystal, a preparation method and an application thereof, which can achieve multi-step circularly polarized luminescence inversion by only adjusting the concentration of chiral luminescent molecules.

[0004] Technical solution: On the one hand, the present invention provides the solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion, including organic small molecules and chiral luminescent molecules as building blocks of cholesteric liquid crystals, and the organic small molecules and chiral luminescent molecules are co-assembled through thermal annealing to form a solid-state cholesteric liquid crystal with circularly polarized luminescence properties.

[0005] Further, the organic small molecule is a cholesterol molecule, wherein the cholesterol molecule includes one or more of β-sitosterol-4-iodocinnamate (4I-CASS), cholesterol-4-iodocinnamate (4I-CACS), and dihydrocholesterol-4-iodocinnamate (4I-CAHCS). As an organic small molecule of liquid crystal building blocks, it can be transformed into a liquid crystal phase under high temperature heating.

[0006] Further, the chiral luminescent molecules include one or more of pyridinium cholesterol and quinoline cholesterol; wherein the pyridinium cholesterol chiral luminescent molecules include one or more of pyridinium sitosterol, pyridinium cholesterol, and pyridinium dihydrocholesterol; the quinoline cholesterol chiral luminescent molecules include one or more of quinoline sitosterol, quinoline cholesterol, and quinoline dihydrocholesterol. As chiral luminescent molecules, by introducing different luminescent groups, they can produce multicolor fluorescence emission in solution and solid state.

[0007] A second aspect of the present invention provides a method for preparing the above-mentioned solid cholesteric liquid crystal, comprising the following steps:

[0008] Step S11, adding solvents to organic small molecules and chiral luminescent molecules to prepare mother solutions of certain concentrations;

[0009] Step S12, adding appropriate amounts of the mother solution of the organic small molecule and the mother solution of the chiral luminescent molecule into a sample bottle, and fully mixing them by ultrasonication;

[0010] Step S13, placing the quartz plate on a heating table for heating;

[0011] Step S14, dropping the sample mixed evenly in step S12 onto the heated quartz plate, then evaporating the solvent, and then covering it with another quartz plate;

[0012] Step S15, removing the quartz plate containing the sample in step S14 from the heating table and performing thermal annealing treatment to obtain a solid cholesteric liquid crystal film;

[0013] Furthermore, the solvent of the mother liquor of the organic small molecule in step S11 is tetrahydrofuran, and the concentration is one or more of 50 mg / mL, 100 mg / mL, and 150 mg / mL; the solvent of the chiral luminescent molecule is tetrahydrofuran, and the concentration is one or more of 5 mg / mL, 10 mg / mL, and 15 mg / mL.

[0014] Furthermore, the total volume of the mixed solvent in step S12 is 100 to 300 μL.

[0015] Furthermore, the weight ratio of the ultrasonic mixing of the organic small molecules and the chiral luminescent molecules described in step S12 is one or more of 0.1wt%, 0.5wt%, 1.0wt%, 3.0wt%, 5.0wt%, 7.0wt%, 9.0wt%, 10.0wt%, 13.0wt%, 15.0wt%, 17.0wt%, 19.0wt%, 20.0wt%, 25.0wt%, 30.0wt%, 35.0wt%, 40.0wt%, 45.0wt%, 50.0wt%, 55.0wt%, 60.0wt%, 65.0wt%, and 70.0wt% (the weight ratio is the ratio of chiral luminescent molecules to organic small molecules).

[0016] Furthermore, the quartz plate heating temperature in step S13 is in the range of 140°C to 160°C.

[0017] Furthermore, the thermal annealing process in step S15 is performed at room temperature, in an ice bath or in a liquid nitrogen environment.

[0018] In the last aspect, the present invention provides the use of the solid-state cholesteric liquid crystal as a circularly polarized light-emitting material.

[0019] Compared with the prior art, the above invention has the following beneficial effects:

[0020] (1) The present invention uses a high-temperature thermotropic liquid crystal building unit as the main body, and co-assembles it with a chiral luminescent molecule through a supramolecular chiral co-assembly strategy. By regulating the concentration of the chiral luminescent molecule, the construction of a multi-step circularly polarized luminescent material can be achieved;

[0021] (2) The circularly polarized luminescent material provided by the present invention can be maintained in a cholesteric liquid crystal phase in the solid state and has circularly polarized luminescence performance and multi-step circularly polarized luminescence signal reversal performance;

[0022] (3) The preparation method provided by the present invention is simple and convenient to operate and is suitable for scale-up production;

[0023] (4) The solid-state cholesteric liquid crystal material constructed by the present invention is applied to information encryption, and encryption display of CPL material is observed in practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1The solid-state cholesteric liquid crystals prepared by the liquid nitrogen cooling thermal annealing process in the embodiments of the present invention are shown in Figure 1, wherein a is a solid-state photo of a cholesteric liquid crystal prepared by mixing cholesterol-4-iodocinnamate (H) and a pyridine cholesterol-type chiral luminescent molecule (G1) in different mass ratios under the irradiation of a fluorescent lamp and 365nm ultraviolet light; b is a solid-state photo of a cholesteric liquid crystal prepared by mixing cholesterol-4-iodocinnamate (H) and a pyridine cholesterol-type chiral luminescent molecule (G2) in different mass ratios under the irradiation of a fluorescent lamp and 365nm ultraviolet light; c is a solid-state photo of a cholesteric liquid crystal prepared by mixing cholesterol-4-iodocinnamate (H) and a pyridine cholesterol-type chiral luminescent molecule (G3) in different mass ratios under the irradiation of a fluorescent lamp and 365nm ultraviolet light. d is a solid-state photograph of a cholesteric liquid crystal prepared by mixing cholesterol-4-iodocinnamate (H) and a pyridine cholesterol-type chiral luminescent molecule (G4) in different mass ratios under the irradiation of a fluorescent lamp and 365nm ultraviolet light; e is a solid-state photograph of a cholesteric liquid crystal prepared by mixing cholesterol-4-iodocinnamate (H) and a quinoline cholesterol-type chiral luminescent molecule (G5) in different mass ratios under the irradiation of a fluorescent lamp and 365nm ultraviolet light; f is a solid-state photograph of a cholesteric liquid crystal prepared by mixing cholesterol-4-iodocinnamate (H) and a pyridine cholesterol-type chiral luminescent molecule (G6) in different mass ratios under the irradiation of a fluorescent lamp and 365nm ultraviolet light;

[0025] Figure 2 Polarized optical microscope (POM) images of solid cholesteric liquid crystals with different weight ratios in the embodiments of the present invention;

[0026] Figure 3 is an X-ray powder diffractometer (XRD) spectrum of solid cholesteric liquid crystals with different weight ratios in the embodiments of the present invention;

[0027] Figure 4 The CPL spectra of solid cholesteric liquid crystals with different weight ratios in the embodiments of the present invention;

[0028] Figure 5 This is an information encryption application of circularly polarized reflection of a solid-state cholesteric liquid crystal film in an embodiment of the present invention, wherein a is a Morse code array setting and its actual picture under natural light, the array is composed of a solid-state cholesteric liquid crystal film and a non-chiral α-DCS film; b is an image of left-handed (LCPF) and right-handed (RCPF) circular polarization filters placed on the top of the solid-state cholesteric liquid crystal film and the non-chiral α-DCS film under natural light; c is a process of multi-level encryption and decryption of the Morse code array using LCPF and RCPF under natural light.

[0029] Figure 6 It is an information encryption application of circularly polarized light emission of solid-state cholesteric liquid crystal film in an embodiment of the present invention;

[0030] Figure 7 Schematic diagram of the chiral optical activity of solid-state cholesteric liquid crystal film and its encryption application, wherein a is a photo of solid-state cholesteric liquid crystal prepared by liquid nitrogen cooling thermal annealing process; b is the CPL spectrum of solid-state cholesteric liquid crystal with different weight ratios; c is the CPL spectrum of solid-state cholesteric liquid crystal with different weight ratios; d is the information encryption application of circularly polarized luminescence of solid-state cholesteric liquid crystal film. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments will be described clearly and completely below. Obviously, the embodiments described below are only part of the embodiments of the present invention, rather than all the embodiments.

[0032] The terms "comprise", "include" and any variations thereof in the following embodiments and comparative examples are intended to cover non-exclusive inclusions, for example, a process, method, or product comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, or products.

[0033] In addition, the experimental methods shown in the following examples are conventional methods unless otherwise specified; the materials and reagents are purchased from commercial sources unless otherwise specified.

[0034] Example 1: Preparation method of 0.5 wt% chiral luminescent molecules / chiral liquid crystal molecules solid cholesteric liquid crystal film:

[0035] 1.1. Add a certain amount of 5 mg / mL tetrahydrofuran mother solution of pyridine cholesterol chiral luminescent molecule (G) to 50 mg / mL tetrahydrofuran mother solution of cholesterol-4-iodocinnamate (4I-CACS, H) chiral liquid crystal molecule, and mix them thoroughly by ultrasonication; the total volume of the solvent is 100-300 μL, the weight ratio of G / H is 0.5wt%, and the ultrasonic power is 100-200W.

[0036] 1.2. Place the quartz plate on a heating table at 150°C and heat for 1 minute, then slowly drop the above-mentioned mixed solution; after the solvent is completely evaporated, continue heating for 2 minutes to transform the sample from a solid phase to a liquid crystal phase, and then cover the sample with another quartz plate to ensure that the liquid crystal is evenly dispersed. Subsequently, the sample is quickly subjected to thermal annealing. The thermal annealing process is one of room temperature cooling, ice bath cooling, and liquid nitrogen cooling. As an example, this embodiment uses liquid nitrogen cooling. After liquid nitrogen cooling annealing for 1 minute, a solid cholesteric liquid crystal film ( Figure 1 ).

[0037] Example 2: Preparation method of 10.0 wt% chiral luminescent molecules / chiral liquid crystal molecules solid cholesteric liquid crystal film:

[0038] 2.1. Add a certain amount of 5 mg / mL tetrahydrofuran mother solution of pyridine cholesterol chiral luminescent molecule (G) to 50 mg / mL tetrahydrofuran mother solution of cholesterol-4-iodocinnamate (4I-CACS, H) chiral liquid crystal molecule, and mix them thoroughly by ultrasonication; the total volume of the solvent is 100-300 μL, the weight ratio of G / H is 10.0 wt%, and the ultrasonic power is 100-200 W.

[0039] 2.2. Place the quartz plate on a heating table at 150°C and heat for 1 minute, then slowly drop the above-mentioned mixed solution; after the solvent is completely evaporated, continue heating for 2 minutes to transform the sample from the solid phase to the liquid crystal phase, and then cover the sample with another quartz plate to ensure that the liquid crystal is evenly dispersed. Subsequently, the sample is quickly subjected to thermal annealing. The thermal annealing process is one of room temperature cooling, ice bath cooling, and liquid nitrogen cooling. As an example, this embodiment uses liquid nitrogen cooling. After liquid nitrogen cooling annealing for 1 minute, a solid cholesteric liquid crystal film ( Figure 1 ).

[0040] Example 3: Preparation method of 20.0 wt% chiral luminescent molecules / chiral liquid crystal molecules solid cholesteric liquid crystal film:

[0041] 3.1. Add a certain amount of 5 mg / mL tetrahydrofuran mother solution of pyridine cholesterol chiral luminescent molecule (G) to 50 mg / mL tetrahydrofuran mother solution of cholesterol-4-iodocinnamate (4I-CACS, H) chiral liquid crystal molecule, and mix them thoroughly by ultrasonication; the total volume of the solvent is 100-300 μL, the weight ratio of G / H is 20.0 wt%, and the ultrasonic power is 100-200 W.

[0042] 3.2. Place the quartz plate on a heating table at 150°C and heat for 1 minute, then slowly drop the above-mentioned mixed solution; after the solvent is completely evaporated, continue heating for 2 minutes to transform the sample from a solid phase to a liquid crystal phase, and then cover the sample with another quartz plate to ensure that the liquid crystal is evenly dispersed. Subsequently, the sample is quickly subjected to thermal annealing. The thermal annealing process is one of room temperature cooling, ice bath cooling, and liquid nitrogen cooling. As an example, this embodiment uses liquid nitrogen cooling. After liquid nitrogen cooling annealing for 1 minute, a solid cholesteric liquid crystal film ( Figure 1 ).

[0043] Example 4: Preparation method of 50.0 wt% chiral luminescent molecules / chiral liquid crystal molecules solid cholesteric liquid crystal film:

[0044] 4.1. Add a certain amount of 5 mg / mL tetrahydrofuran mother solution of pyridine cholesterol chiral luminescent molecule (G) to 50 mg / mL tetrahydrofuran mother solution of cholesterol-4-iodocinnamate (4I-CACS, H) chiral liquid crystal molecule, and mix them thoroughly by ultrasonication; the total volume of the solvent is 100-300 μL, the weight ratio of G / H is 50.0 wt%, and the ultrasonic power is 100-200 W.

[0045] 4.2. Place the quartz plate on a heating table at 150°C and heat for 1 minute, then slowly drop the above-mentioned mixed solution; after the solvent is completely evaporated, continue heating for 2 minutes to transform the sample from the solid phase to the liquid crystal phase, and then cover the sample with another quartz plate to ensure that the liquid crystal is evenly dispersed. Subsequently, the sample is quickly subjected to thermal annealing. The thermal annealing process is one of room temperature cooling, ice bath cooling, and liquid nitrogen cooling. As an example, this embodiment uses liquid nitrogen cooling. After liquid nitrogen cooling annealing for 1 minute, a solid cholesteric liquid crystal film ( Figure 1 ).

[0046] The organic small molecules in the above embodiments can be replaced by one or more of other β-sitosterol-4-iodocinnamate or dihydrocholesterol-4-iodocinnamate as needed.

[0047] The concentration of the organic small molecules in the above embodiments can be replaced with one or more of 100 mg / mL and 150 mg / mL as needed.

[0048] The chiral luminescent molecules in the above embodiments can be replaced by one or more other pyridostanol or pyridinium dihydrocholesterol or other quinoline cholesterol chiral luminescent molecules as needed.

[0049] The concentration of the chiral luminescent molecules in the above embodiments can be replaced with one or more of 10 mg / mL and 15 mg / mL as needed.

[0050] Example 5: Confirmation of solid cholesteric liquid crystal

[0051] Experimental methods:

[0052] Polarizing microscope and X-ray powder diffraction pattern detection, the 0.5wt% G / H, 10.0wt% G / H, 20.0wt% G / H, and 50.0wt% G / H films obtained in Example 1 to Example 4 were placed under a polarizing microscope and an X-ray powder diffractometer, respectively, to observe their liquid crystal texture and diffraction peaks.

[0053] Test results:

[0054] The polarizing microscope ( Figure 2 ) analysis, it was observed that there was an oily filamentous texture in the solid film, indicating that the solid-state cholesteric liquid crystal material was successfully prepared.

[0055] The XRD patterns of 0.5wt% G / H, 10.0wt% G / H, 20.0wt% G / H and 50.0wt% G / H films were analyzed. Figure 3 ) analysis, typical liquid crystal diffraction peaks were observed, further indicating that a solid cholesteric liquid crystal material was prepared.

[0056] Example 6: Circularly polarized luminescence of solid-state cholesteric liquid crystal

[0057] Experimental methods:

[0058] For detection of circularly polarized luminescence spectra, 0.5wt% G / H, 10.0wt% G / H, 20.0wt% G / H, and 50.0wt% G / H solid cholesteric liquid crystals obtained in Examples 1 to 4 were respectively placed in a circularly polarized spectrometer to measure their chiral luminescence.

[0059] Test results:

[0060] Through the CPL spectra of 0.5wt% G / H, 10.0wt% G / H, 20.0wt% G / H, 50.0wt% G / H solid cholesteric liquid crystal ( Figure 4 ) analysis showed that at a doping ratio of 0.5wt%, the prepared cholesteric liquid crystal film showed a right-handed CPL signal; as the doping ratio increased to 10.0wt%, the CPL signal turned into left-handed; when the doping ratio was further increased to 20.0wt%, the CPL signal was reversed to right-handed again; when the proportion of chiral luminescent molecules was further increased to 50.0wt%, the CPL signal returned to left-handedness.

[0061] Example 7: Application of circularly polarized reflection information encryption in solid-state cholesteric liquid crystal film

[0062] Experimental methods:

[0063] The solid cholesteric liquid crystal films obtained in Examples 1 to 4 and the non-chiral fluorescent molecules (α-DCS) are combined to form an array ( Figure 5 ) is used for Morse code reading. In this array, two consecutive lattices represent the "-" in Morse code, while a single lattice represents "·".

[0064] Test results:

[0065] By analyzing the reflection color intensity of cholesteric liquid crystal film and α-DCS film under left-handed and right-handed circular polarization filters (LCPF and RCPF), it was found that when the cholesteric liquid crystal film was placed on the LCPF, the reflection color hardly changed; and after replacing it with the RCPF, the reflection color became significantly darker. In contrast, the reflection color of α-DCS did not change significantly regardless of whether the LCPF or RCPF was placed. Further, when the array composed of cholesteric liquid crystal film and α-DCS film was observed with a circular polarizer, it was found that when the LCPF was placed on the array, the observed Morse code corresponded to the initial value "0000". However, when the RCPF was placed on the array, the Morse code changed significantly, and the real password "2025" was finally output.

[0066] Example 8: Application of circularly polarized luminescence information encryption in solid-state cholesteric liquid crystal films

[0067] Experimental methods:

[0068] The solid cholesteric liquid crystal films obtained in Examples 1 to 4 and the non-chiral fluorescent molecules (α-DCS) are combined to form an array ( Figure 5 ) is used for Morse code reading. In this array, two consecutive lattices represent the "-" in Morse code, while a single lattice represents "·".

[0069] Test results:

[0070] By analyzing the circularly polarized luminescence intensity of the array composed of cholesteric liquid crystal film and α-DCS film under left-handed and right-handed circular polarization filters (LCPF and RCPF) under 365nm light source, it was found that the array initially emitted green fluorescence under 365nm irradiation and could only read the wrong password "000". When the array was placed under the LCPF, a real dynamic password "ChAǔǔ" could be read from the green fluorescent lattice, and another real dynamic password "TJU" could be decrypted from the fluorescence change area.

[0071] From the test results of the above embodiments and application examples, it can be seen that the present invention prepares a solid-state cholesteric liquid crystal film with multi-step circularly polarized luminescence inversion through a relatively simple method, which can reduce the construction cost of circularly polarized luminescent materials; it has the properties of chirality inversion and high luminescence asymmetry factor, and has strong compatibility and a wide range of applications.

[0072] In summary, the present invention discloses a preparation method and application of a solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence reversal. The solid-state cholesteric liquid crystal includes organic small molecules and chiral luminescent molecules as building blocks of cholesteric liquid crystal; the organic small molecules and chiral luminescent molecules are co-assembled during thermal annealing to form a solid-state cholesteric liquid crystal with circularly polarized luminescence properties; the present invention uses high-temperature cholesteric liquid crystal building blocks as main molecules and chiral luminescent molecules as guest molecules, and realizes the construction of a full-color circularly polarized luminescent liquid crystal material by regulating the luminescent color and concentration of the chiral luminescent molecules; the liquid crystal material achieves the reversal of multi-step circularly polarized luminescence signals by precisely regulating the concentration of the chiral luminescent molecules, and exhibits a significant luminescence asymmetry factor. This material has excellent circularly polarized luminescence performance, laying a solid foundation for its application in the field of advanced information encryption; the material preparation method is simple and convenient to operate, and is suitable for scale-up production.

[0073] Those skilled in the art should understand that those skilled in the art can implement variations by combining the prior art and the above embodiments, which will not be described in detail here. Such variations do not affect the essential content of the present invention, and will not be described in detail here.

[0074] The above describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the devices and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes, which does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention are still within the scope of protection of the technical solutions of the present invention.

Claims

1. A solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion, characterized in that: Solid-state cholesteric liquid crystals with circularly polarized luminescence properties are formed by co-assembly of organic small molecules and chiral luminescent molecules through thermal annealing.

2. The solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion according to claim 1, characterized in that: The organic small molecule is a cholesterol molecule, including one or more of β-sitosterol-4-iodocinnamate, cholesterol-4-iodocinnamate or dihydrocholesterol-4-iodocinnamate.

3. The solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion according to claim 1, characterized in that: The chiral luminescent molecules include one or more pyridine cholesterol chiral luminescent molecules or quinoline cholesterol chiral luminescent molecules; the pyridine cholesterol chiral luminescent molecules include one or more pyridine sitosterols, pyridine cholesterols or pyridine dihydrocholesterols; the quinoline cholesterol chiral luminescent molecules include one or more quinoline sitosterols, quinoline cholesterols or quinoline dihydrocholesterols.

4. The method for preparing a solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S11, adding solvents to organic small molecules and chiral luminescent molecules to prepare mother solutions of certain concentrations; Step S12, ultrasonically mixing an appropriate amount of a mother solution of an organic small molecule and a mother solution of a chiral luminescent molecule; Step S13, heating the quartz plate; Step S14, dropping the sample in step S12 onto the heated quartz plate, then evaporating the solvent, and then covering it with another quartz plate; Step S15: remove the quartz plate containing the sample in step S14 from the heating table and perform thermal annealing to obtain a solid cholesteric liquid crystal film.

5. The method for preparing a solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion according to claim 4, characterized in that: The solvent of the mother liquor of the organic small molecule in step S11 is tetrahydrofuran, and the concentration is one or more of 50 mg / mL, 100 mg / mL, and 150 mg / mL; the solvent of the chiral luminescent molecule is tetrahydrofuran, and the concentration is one or more of 5 mg / mL, 10 mg / mL, and 15 mg / mL.

6. The method for preparing a solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion according to claim 4, characterized in that: The total volume of the mixed solvent in step S12 is 100 to 300 μL.

7. The method for preparing a solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion according to claim 4, characterized in that: The weight ratio of the ultrasonic mixing of the organic small molecules and the chiral luminescent molecules described in the step S12 is 0.1wt%, 0.5wt%, 1.0wt%, 3.0wt%, 5.0wt%, 7.0wt%, 9.0wt%, 10.0wt%, 13.0wt%, 15.0wt%, 17.0wt%, 19.0wt%, 20.0wt%, 25.0wt%, 30.0wt%, 35.0wt%, 40.0wt%, 45.0wt%, 50.0wt%, 55.0 wt%, 60.0wt%, 65.0wt% or 70.0wt%.

8. The method for preparing a solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion according to claim 4, characterized in that: The quartz plate heating temperature in step S13 is in the range of 140°C to 160°C.

9. The method for preparing a solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion according to claim 4, characterized in that: The thermal annealing process in step S15 is performed at room temperature, in an ice bath or in a liquid nitrogen environment.

10. Application of the solid-state cholesteric liquid crystal with multi-step circularly polarized luminescence inversion as claimed in any one of claims 1 to 3 as a circularly polarized luminescent material in the field of advanced information encryption.

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