Photoresponsive blue phase liquid crystal composite material with chiral flipping performance and photonic crystal thin film

Abstract

The application discloses a kind of light response blue phase liquid crystal composite material with chiral flip performance and photonic crystal film, belong to functional liquid crystal material technical field, the light response blue phase liquid crystal composite material component includes: 60.0%-95.0% small molecule nematic phase liquid crystal A, 0.1%-15.0% chiral helonene compound B, and 0.1%-30.0% chiral compound C;The prepared photonic crystal film presents wide blue phase temperature domain, photonic crystal self-assembly performance is excellent, reflection photonic band gap controllable range is large and the like advantages by simple process, with reflection photonic band gap waveband (continuity or jump) movement, circular polarization state chiral flip and liquid crystal phase behavior change and the like reversible control function.

Description

Technical Field

[0001] This invention belongs to the field of functional liquid crystal materials technology, specifically relating to a photoresponsive blue phase liquid crystal composite material and a photonic crystal thin film with chiral reversal properties. Background Technology

[0002] Blue phase (BP) liquid crystals are a special phase state between isotropic and cholesteric liquid crystals. In BP liquid crystals, chiral liquid crystal molecules form double-twisted cylinders through a double-twisted arrangement and further self-assemble into supramolecular crystal structures. Based on the symmetry of the crystal spatial structure, BP can be roughly divided into three sub-phases: body-centered cubic blue phase I (BPI), simple cubic blue phase II (BPII), and amorphous blue phase III (BPIII). Among them, the self-assembled periodic structures of BPI and BPII can form three-dimensional blue phase photonic crystal materials, exhibiting unique selective reflection characteristics on different crystal planes, that is, selectively reflecting left-handed (or right-handed) circularly polarized photons that obey Bragg's law. Therefore, blue phase photonic crystal materials have broad application prospects in ultrafast response displays, reflective displays, tunable lasers, and optical communications.

[0003] Chinese patent document CN102786935A discloses a blue phase liquid crystal composite material, comprising blue phase liquid crystal and ferroelectric nanoparticles. The mass percentage of the blue phase liquid crystal is 98.0%~99.95%, and the mass percentage of the ferroelectric nanoparticles is 0.05%~2.0%. The ferroelectric nanoparticles are barium titanate nanoparticles, tin sulfide phosphide nanoparticles, lithium niobate nanoparticles, or lead titanate nanoparticles. This blue phase liquid crystal composite material has a fast response speed to an electric field, low driving voltage, and the ability to achieve reversible recovery of the blue phase liquid crystal under an electric field. Chinese patent document CN113004909A discloses a composite stable blue phase liquid crystal composition, comprising a blue phase liquid crystal matrix, in which surface-modified nanoparticles and a polymer polymerized from photopolymerizable monomers are doped. This invention effectively broadens the blue phase temperature range of blue phase liquid crystal materials by incorporating surface-modified nanoparticles and polymers synthesized from photopolymer monomers into a blue phase liquid crystal matrix formed by combining a chiral agent and a nematic liquid crystal host.

[0004] Generally, the temperature range in which blue phase liquid crystals can stably exist is only about 1°C, which greatly limits their application range. Although the aforementioned patents introduce responsive functional molecules / nanomaterials into blue phase liquid crystal composite materials, they can use electric fields, temperature, light irradiation, etc. to control the wavelength shift of the photonic bandgap of blue phase photonic crystals within a certain wavelength range, but the controllable range is still very limited. Therefore, it is necessary to develop new blue phase liquid crystal composite material systems to broaden the temperature range of blue phase. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a photoresponsive blue phase liquid crystal composite material with chiral reversal properties. Its temperature range is 5-30 °C. It can self-assemble into a blue phase photonic crystal thin film through simple annealing. The corresponding reflective photonic bandgap has a reversible controllable range from ultraviolet to near-infrared bands, and can realize the mutual reversal between left-handed and right-handed circular polarization states.

[0006] The specific technical solution adopted is as follows: A photoresponsive blue phase liquid crystal composite material with chiral reversal properties comprises, by mass percentage: 60.0%-99.5% small molecule nematic liquid crystal A, 0.1%-15.0% chiral helicene compound B, and 0.1%-30.0% chiral compound C; Chiral helicene compound B is selected from at least one of the compounds (1)-(4) shown below: ; Among them, R1, R 2、 R3 and R4 are each independently selected from H atoms, aromatic groups, alkyl groups, or substituents containing O atoms, N atoms, F atoms, or S atoms; X is selected from methyl, phenyl, isopropyl, or tert-butyl; Y and Z are each independently selected from H atoms, O atoms, or S atoms; m and n are each independently 0 or 1. Chiral compound C is selected from at least one of the following compounds: .

[0007] This invention introduces chiral helicene compounds with specific structures into small-molecule nematic liquid crystals, and then adds appropriate amounts of one or more chiral compounds to obtain a photoresponsive blue phase liquid crystal composite material with a wide temperature range of 5-30 °C.

[0008] Furthermore, the small molecule nematic liquid crystal A is a low-viscosity nematic mixture with a viscosity <50 mPa, a melting point <-10℃, and a clearing point in the range of 30~200℃.

[0009] Specifically, the small molecule nematic liquid crystal A is selected from commercial products such as SLC1717, PTO-003, PTO-005, HTG1352005, and HTG1352005-OXD.

[0010] Furthermore, R1, R 2、 R3 and R4 are each independently selected from H atom, mercapto, hydroxyl, carboxyl, phosphate, sulfonic acid, sulfate, ammonium, phenyl, acrylate, sodium acrylate, acrylamide, salicylaniline, salicylaniline or any of the substituents shown in formulas (5)-(16); in substituents (5)-(16), n is an integer from 1 to 12; .

[0011] The present invention also provides a photonic crystal thin film comprising the aforementioned photoresponsive blue phase liquid crystal composite material.

[0012] Furthermore, the photonic crystal thin film is prepared by the following method: adding the photoresponsive blue phase liquid crystal composite material into a liquid crystal cell, or injecting the photoresponsive blue phase liquid crystal composite material into a liquid crystal thin film, heating and holding at a certain temperature, and then annealing to obtain the photonic crystal thin film.

[0013] Preferably, small molecule nematic liquid crystal A, chiral helicene compound B and chiral compound C are taken, mixed evenly, and then poured into a liquid crystal cell. The thickness is controlled by spacers or glass microspheres, so that the thickness is in the range of 2 μm to 300 μm.

[0014] Preferably, the liquid crystal is heated to 0.1-10.0 °C above the clearing point of the small molecule nematic liquid crystal A and held at that temperature for 1.0-60.0 minutes. Then, it is subjected to annealing heat treatment at a rate of 0.01-5.0 °C / minute. When the temperature drops to the blue phase liquid crystal temperature range, it self-assembles to form a blue phase photonic crystal thin film with uniform crystal surface reflection.

[0015] Furthermore, when photonic crystal films are irradiated with excitable light from chiral helicene compound B, the photonic crystal films exhibit different dynamic photoresponse behaviors as the irradiation time or intensity increases. These behaviors include (continuous or abrupt) shifts in the reflected photonic bandgap, chiral reversal of circular polarization states, and changes in liquid crystal phase behavior.

[0016] This invention combines chiral helicene compounds with photoisomerization behavior with light irradiation conditions to achieve band shifting of the reflected photonic bandgap in blue phase photonic crystal thin films. The reversible modulation range covers the ultraviolet to near-infrared band, and it can also flip from a left-handed (or right-handed) circular polarization state to a right-handed (or left-handed) circular polarization state. Furthermore, the added chiral helicene compounds exhibit chiral reversal characteristics under excitable light irradiation. That is, as the irradiation time or intensity increases, the helical twisting force of the chiral helicene compounds gradually weakens in left-handed (or right-handed) optical activity until it runs out, and then chiral reversal occurs, gradually increasing in right-handed (or left-handed) optical activity.

[0017] Because lattice Bragg reflection in blue phase photonic crystal thin films must satisfy the following relationship: In the formula, λ , n and a These are the incident light wavelength, the liquid crystal refractive index, and the blue phase lattice constant, respectively. h , k , l The crystal plane indices of the blue phase lattice. When the doping concentration of the chiral material is constant, the blue phase lattice constant is... a Cholesterol phase pitch p Similarly, its magnitude is inversely related to the overall helical twisting power (HTP) of the chiral material. Therefore, as the excitation light irradiation time or intensity increases, the reflected photonic bandgap of the blue phase photonic crystal thin film of this invention will exhibit corresponding band shifts, chiral flips, and liquid crystal phase transitions due to changes in the overall HTP of the blue phase liquid crystal material. Furthermore, when the overall HTP decreases, the blue phase lattice constant... a As the overall HTP increases, the reflected photonic bandgap redshifts towards longer wavelengths; when the overall HTP increases, the blue phase lattice constant... aAs the overall HTP decreases, the reflected photonic bandgap shifts towards shorter wavelengths (blue shift). When the overall HTP decreases to a certain extent, and the blue phase lattice constant α increases to a certain extent, the liquid crystal phase changes from BPII to BPI. The reflected photonic bandgap of BPII disappears, and the reflected photonic bandgap of BPI appears. The inconsistency in wavelength between these two reflected photonic bandgap patterns leads to a jump shift in the reflected photonic bandgap. As the overall HTP continues to decrease to near zero, the liquid crystal phase changes from a blue phase photonic crystal to a cholesteric, unoriented phase. The focal cone texture and the nematic phase's oil filament texture completely disappear the reflected photonic bandgap. When the overall HTP decreases to near 0 and then gradually increases again, the liquid crystal phase undergoes a chiral reversal to the opposite chiral direction and transforms back from the nematic and cholesteric phases into the blue phase. At this time, the reflected photonic bandgap with the opposite chiral direction also reappears. When the excitation light irradiation is stopped, the overall HTP, the liquid crystal phase, and its reflected photonic bandgap will undergo reversible dynamic recovery, and the recovery rate is determined by the chemical kinetics of the chiral helicene compound.

[0018] In the above-described method for controlling the irradiation of blue phase photonic crystal thin films using excitation light, the preferred excitation light irradiation conditions include: a wavelength of 300-500 nm (any wavelength band capable of exciting photoisomerization of chiral helicene compounds), an irradiation time of 1 s - 1 h, and an irradiation light intensity of 1 μW / cm². 2 - 500 mW / cm 2 .

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The photoresponsive blue phase liquid crystal composite material of the present invention includes chiral helicene compounds, which have the characteristics of spatial three-dimensional biaxial configuration, rapid photoinduced isomerization motion, large helical twisting force, chiral reversal, and excitation light intensity addressing. Therefore, the photoresponsive blue phase liquid crystal composite material based on chiral helical compounds exhibits advantages such as a wide blue phase temperature range (up to ~16 ℃), excellent photonic crystal self-assembly performance, and a large range of tunable reflective photonic bandgap (from ultraviolet to near-infrared band, and has chiral reversal performance).

[0020] 2. The photoresponsive blue phase liquid crystal composite material of the present invention uses widely available materials, is simple to synthesize, and the blue phase photonic crystal thin film is easy to prepare. It can be obtained through simple annealing treatment, is inexpensive, easy to process, and is conducive to large-area production.

[0021] 3. By adjusting the types and proportions of small molecule nematic liquid crystal A, chiral helicene compound B, and chiral compound C, and by regulating the wavelength of the excitation light, the intensity of the irradiation, the ambient temperature, and the substrate and thickness of the liquid crystal device, blue phase photonic crystal thin films with different modulation modes, different modulation speeds, and different display modes can be obtained. Attached Figure Description

[0022] Figure 1 The graph shows the change of HTP of the chiral helicene compound in Comparative Example 1 with irradiation time under different irradiation intensities.

[0023] Figure 2 The phase behavior diagram shows the temperature range of the photoresponse blue phase photonic crystal thin film of Example 1 and its reflected photonic bandgap under different irradiation intensities.

[0024] Figure 3 Polarized light microscope images and Kossel diffraction images of the photoresponsive blue phase photonic crystal thin film of Example 1 under different temperatures and irradiation intensities.

[0025] Figure 4 The dynamic changes in the reflected photonic bandgap of the photoresponsive blue phase photonic crystal thin film (41.5℃) in Example 1 under different irradiation intensities are shown.

[0026] Figure 5 The dynamic change of the reflected photonic bandgap of the blue phase photonic crystal thin film (41.5°C) in Example 1 after the irradiation light was turned off.

[0027] Figure 6 The dynamic changes in the reflected photonic bandgap of the photoresponsive blue phase photonic crystal thin film (40.5℃) in Example 1 under different irradiation intensities are shown.

[0028] Figure 7 The dynamic change of the reflected photonic bandgap of the blue phase photonic crystal thin film (40.5°C) in Example 1 after the irradiation light was turned off.

[0029] Figure 8 The phase behavior diagram shows the temperature range of the photoresponse blue phase photonic crystal thin film and its reflected photonic bandgap under different irradiation intensities in Example 2.

[0030] Figure 9 This describes the reversible modulation process of the reflected photonic bandgap of the blue phase photonic crystal thin film in Example 2 at 50.5℃.

[0031] Figure 10 The phase behavior diagram shows the temperature range of the photoresponse blue phase photonic crystal thin film and its reflected photonic bandgap under different irradiation intensities in Example 3.

[0032] Figure 11 This describes the reversible modulation process of the reflected photonic bandgap of the blue phase photonic crystal thin film in Example 3 at 40.0℃. Detailed Implementation

[0033] To make the objectives, features, and advantages of this invention more apparent and understandable, a detailed description is provided below through specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the invention can be combined appropriately without mutual conflict.

[0034] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer. Contents not described in detail in this specification are prior art known to those skilled in the art. Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0035] Comparative Example 1 This comparative example is used to study the photoresponse HTP change and chiral reversal performance of chiral helicene compounds in liquid crystal composite systems.

[0036] The structural formulas of the chiral helioene compounds in this comparative example are as follows:

[0037] A cholesteric liquid crystal composite system was prepared by blending chiral helicene compounds (levorotatory) with small molecule nematic liquid crystal PTO-003 at a mass ratio of 1.00 / 99.00. The blue phase behavior in this system could not be induced by heating and annealing. However, the photoresponse pitch change and chiral reversal properties of the chiral helicene compounds could be studied by observing the photoresponse pitch change of this cholesteric liquid crystal composite system, as detailed below.

[0038] The cholesteric phase liquid crystal composite system was injected into a wedge-shaped cell (KCRK-07) and irradiated with 365 nm light. The HTP of the chiral spiroene compound used as a function of irradiation time was as follows: Figure 1 As shown. From Figure 1 It can be seen from this that at a light intensity of 0.2 mW / cm², -2 Under irradiation, the HTP of this chiral helicene compound decreased with increasing irradiation time and eventually stabilized. When the light intensity increased to 1.0 mW cm⁻¹, the HTP of the compound decreased. -2 When irradiated for the above duration, the HTP of chiral helicenes will flip from left-handed to right-handed chirality, and will increase with the extension of irradiation time, eventually stabilizing.

[0039] Example 1 This embodiment is used to study the changes in photoresponse phase behavior and photodriven photonic bandgap of a blue phase liquid crystal composite system based on chiral helixene compounds.

[0040] The structural formula of the chiral helioene compound in this embodiment is as follows: .

[0041] First, a photoresponsive blue phase liquid crystal composite system was prepared by blending chiral helicene compounds (dextral) / S5011 (levorotatory) / CB15 (dextral) / small molecule nematic liquid crystal PTO-005 in a ratio of 3.8 / 2.0 / 18.2 / 76.0 (wt%). Then, the liquid crystal composite system was injected into a liquid crystal cell (the thickness of the photoresponsive blue phase liquid crystal composite material was 20 μm), and the temperature was raised to 5.0 ℃ above the clearing point temperature of PTO-005 and held for 20.0 minutes. The system was then subjected to different intensities of ultraviolet light (365 nm) (0.0-45.2 mW cm⁻¹). -2 The temperature was lowered to the blue phase liquid crystal temperature range at a rate of 2.0 °C / min, allowing it to self-assemble into a blue phase photonic crystal thin film. The state of its reflected photonic bandgap was then detected by a fiber optic spectrometer.

[0042] like Figure 2 As shown, the initial phase behavior of the photoresponsive blue phase photonic crystal thin film is an isotropic state: -44.5 ℃ - BPII - 41.2 ℃ - BPII - 39.0 ℃ - cholesteric phase. Regarding the liquid crystal phase behavior, with increasing ultraviolet light intensity, a decrease in clearing point, an increase in the BPII-BPI phase transition temperature, a narrowing of the BPII temperature range, and a broadening of the BPI temperature range can be observed. The crystal structures and reflective crystal planes of BPII and BPI were determined based on Kossel diffraction patterns. Figure 3 ).

[0043] Taking 0.3 °C above the BPII-BPI phase transition point as an example, i.e. at 41.5 °C, the photonic bandgap of the (100) reflective crystal plane of the initial self-assembled BPII photonic crystal is located at 407.8 nm; as the intensity of irradiated ultraviolet light increases, the peak of the reflective photonic bandgap redshifts; when the intensity of irradiated ultraviolet light reaches 9.6 mW cm⁻¹ -2 At 34.5 seconds, BPII rapidly transforms into BPI. The photonic bandgap of the original BPII reflective crystal plane (100) disappears at 522.7 nm, while the photonic bandgap of the BPI reflective crystal plane (110) appears at 587.8 nm, gradually redshifting and stabilizing at 624.3 nm. As the intensity of the irradiated ultraviolet light continues to increase, the BPII-BPI phase transition time shortens. When the intensity of the irradiated ultraviolet light reaches 72.3 mW cm⁻¹, the transition time is further shortened. -2 The BPI reflective crystal plane (110) eventually redshifts and stabilizes at 867.3 nm. Figure 4When the ultraviolet irradiation is turned off, BPI will revert back to BPII at 520 nm and recover to its initial state within 90 seconds. Figure 5 ).

[0044] Taking 0.7 °C below the BPII-BPI phase transition point as an example, i.e. at 40.5 °C, the photonic bandgap of the reflecting crystal plane (110) of the initial self-assembled BPI photonic crystal is located at 473.5 nm; as the intensity of the irradiated ultraviolet light increases, the peak of the reflecting photonic bandgap shows a continuous redshift; when the intensity of the irradiated ultraviolet light reaches 72.3 mW cm⁻¹, the bandgap is further shifted to 473.5 nm. -2 The BPI reflective crystal plane (110) eventually redshifts and stabilizes at 846.8 nm. Figure 6 When the ultraviolet irradiation is turned off, the reflected photonic bandgap of the BPI will return to its initial state within 90 seconds. Figure 7 ).

[0045] Example 2 This embodiment is used to study the changes in the photoresponse phase behavior of a blue phase liquid crystal composite system based on chiral helixene compounds.

[0046] The structural formula of the chiral helioene compound in this embodiment is as follows: .

[0047] First, a photoresponsive blue phase liquid crystal composite system was prepared by blending chiral helicene compounds (levorotatory) / S5011 (levorotatory) / S811 (levorotatory) / nematic liquid crystal HTG1352005 in a ratio of 2.0 / 2.0 / 12.0 / 84.0 (wt%). Then, the liquid crystal composite system was injected into a liquid crystal cell (the thickness of the photoresponsive blue phase liquid crystal composite material was 50 μm), and the temperature was raised to 3.0 °C above the clearing temperature of HTG1352005 and held for 30.0 minutes. The system was then subjected to different intensities of blue light (420 nm) (0.0-47.0 mW cm⁻¹). -2 The temperature was lowered to the blue phase liquid crystal temperature range at a rate of 0.5 °C / min, causing it to self-assemble into a blue phase photonic crystal thin film, and the state of its reflected photonic bandgap was detected by a fiber optic spectrometer.

[0048] like Figure 8 As shown, the initial phase behavior of the photoresponsive blue phase photonic crystal thin film is an isotropic state of -53.0 ℃-BPII-50.0 ℃-BPII-47.0 ℃-cholesterol phase. With the increase of blue light intensity, it can be found that the clearing point of the photoresponsive blue phase liquid crystal composite system decreases, the BPII-BPI phase transition temperature increases, the BPII temperature range narrows, and the BPI temperature range widens.

[0049] Taking 0.5 °C above the BPII-BPI phase transition point as an example, i.e. at 50.5 °C, the photonic bandgap of the reflecting crystal plane (100) of the initially self-assembled BPII photonic crystal is 378.0 nm; at 47.0 mW / cm², the bandgap is... -2 Under strong blue light irradiation, the peak of the reflected photonic bandgap redshifts. The original BPII reflective crystal plane (100) photonic bandgap disappears at 471.8 nm, while the BPI reflective crystal plane (110) photonic bandgap appears at 523.6 nm, eventually redshifting and stabilizing at 803.1 nm. When the irradiation is turned off, the BPI reflected photonic bandgap recovers to its initial state within 100 seconds. Figure 9 As shown, the reversible control process of the photoresponse blue phase photonic crystal is illustrated from top to bottom as the optical texture of the polarizing microscope, a schematic diagram of the blue phase photonic crystal structure, and the dynamic control displacement of the reflected photonic bandgap.

[0050] Example 3 This embodiment is used to verify the changes in photoresponse phase behavior and photodriven photonic bandgap of a blue phase liquid crystal composite system based on chiral helixene compounds.

[0051] The structural formula of the chiral helioene compound in this embodiment is as follows: .

[0052] First, a photoresponsive blue phase liquid crystal composite system was prepared by blending chiral helicene (dextral) / R5011 (dextral) / nematic liquid crystal HTG1352005-OXD in a ratio of 13.5 / 0.5 / 86.0 (wt%). Then, the liquid crystal composite system was injected into a liquid crystal cell (the thickness of the photoresponsive blue phase liquid crystal composite material was 8 μm), and the temperature was raised to 2.0 °C above the clearing point temperature of HTG1352005-OXD and held for 5.0 minutes. Under different intensities of ultraviolet light (350 nm) (0.0 - 49.4 mW cm⁻¹), the light intensity was measured. -2 The temperature was lowered to the blue phase liquid crystal temperature range at a rate of 0.1 °C / min, causing it to self-assemble into a blue phase photonic crystal thin film, and the state of its reflected photonic bandgap was detected by a fiber optic spectrometer.

[0053] like Figure 10 As shown, the initial phase behavior of the photoresponsive blue phase photonic crystal thin film is an isotropic state of -42.8 ℃-BPII-27.3 ℃-cholester phase. With the increase of ultraviolet light intensity, it can be found that the clearing point of the photoresponsive blue phase liquid crystal composite system decreases, the phase transition temperature of BPII-cholester phase increases, and the BPII temperature range shifts to a lower temperature.

[0054] At 40.0 °C, the initial state of the self-assembled BPII photonic crystal has a photonic bandgap of 426.1 nm on the (100) reflective plane; at 49.4 mW / cm², the bandgap is... -2 Under intense irradiation, the peak of the reflected photonic bandgap redshifts continuously to 901.3 nm and disappears. With increasing irradiation time, the dextrorotatory HTP of the chiral helicene continuously decreases, and the blue phase transforms into the cholesteric and nematic phases. When the chiral helicene undergoes chiral inversion, its levorotatory HTP continuously increases, and the nematic phase transforms into the cholesteric and blue phases. The reflected photonic bandgap of the blue phase photonic crystal reappears at 826.7 nm, exhibiting continuous blue color, and eventually stabilizes at 452.8 nm. When the ultraviolet irradiation is turned off, the reflected photonic bandgap of the BPI recovers to its initial state within 250 seconds. Figure 11 As shown, the reversible control process of the photoresponsive blue phase photonic crystal is illustrated from top to bottom as the optical texture of the polarizing microscope, the schematic diagram of the liquid crystal structure, and the dynamic control displacement of the reflected photonic bandgap.

[0055] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A photoresponsive blue phase liquid crystal composite material with chiral reversal properties, characterized in that, By mass percentage, the components include: 60.0%-99.5% small molecule nematic liquid crystal A, 0.1%-15.0% chiral helicene compound B, and 0.1%-30.0% chiral compound C; Chiral helicene compound B is selected from at least one of the compounds (1)-(4) shown in the following formulas: ； Among them, R1, R 2、 R3 and R4 are each independently selected from H atoms, aromatic groups, alkyl groups, or substituents containing O atoms, N atoms, F atoms, or S atoms; X is selected from methyl, phenyl, isopropyl, or tert-butyl; Y and Z are each independently selected from H atoms, O atoms, or S atoms; m and n are each independently 0 or 1; Chiral compound C is selected from at least one of the following compounds: 。 2. The photoresponsive blue phase liquid crystal composite material according to claim 1, characterized in that, Small molecule nematic liquid crystal A is a low-viscosity nematic mixture with a viscosity <50 mPa, a melting point <-10 ℃, and a clearing point in the range of 30 ~ 200 ℃.

3. The photoresponsive blue phase liquid crystal composite material according to claim 1, characterized in that, R1, R 2、 R3 and R4 are each independently selected from H atom, mercapto, hydroxyl, carboxyl, phosphate, sulfonic acid, sulfate, ammonium, phenyl, acrylate, sodium acrylate, acrylamide, salicylaniline, salicylaniline or any of the substituents shown in formulas (5)-(16); in substituents (5)-(16), n is an integer from 1 to 12; 。 4. A photonic crystal thin film, characterized in that, It includes the photoresponsive blue phase liquid crystal composite material according to any one of claims 1-3.

5. The photonic crystal thin film according to claim 4, characterized in that, The photonic crystal film is prepared by the following method: adding the photoresponsive blue phase liquid crystal composite material into a liquid crystal cell, or injecting the photoresponsive blue phase liquid crystal composite material into a liquid crystal film, heating and holding at a certain temperature, and then annealing to obtain the photonic crystal film.

6. The photonic crystal thin film according to claim 5, characterized in that, The thickness of the photoresponsive blue phase liquid crystal composite material is 2 μm - 300 μm.

7. The photonic crystal thin film according to claim 5, characterized in that, Heat to 0.1-10.0 °C above the clearing point of the small molecule nematic liquid crystal A, and hold for 1.0-60.0 minutes, then anneal at a rate of 0.01-5.0 °C / min.

8. The photonic crystal thin film according to claim 4, characterized in that, When photonic crystal films are irradiated with excitation light, they exhibit different dynamic behaviors in their photoresponse as the irradiation time or intensity increases. These behaviors include shifts in the bandgap of reflected photonics, chiral reversal of circularly polarized states, and changes in liquid crystal phase behavior.

9. The photonic crystal thin film according to claim 8, characterized in that, Excitation light irradiation conditions include: wavelength 300-500 nm, irradiation light intensity of 1 μW / cm². 2 - 500 mW / cm 2 .

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