Chiral photosensitive molecular switch, cholesteric liquid crystal composition, display panel and preparation method of display panel

Abstract

The invention provides a chiral photosensitive molecular switch, a cholesteric liquid crystal composition, a display panel and a preparation method of the display panel. The chiral photosensitive molecular switch has two steady states, can be converted from one steady state to the other steady state in response to illumination, and stably exists. The cholesteric liquid crystal composition comprises a chiral photosensitive molecular switch, a bending type molecular mixture, a rod-like single crystal mixture and a non-photosensitive chiral dopant, the cholesteric liquid crystal composition can be used for preparing a cholesteric liquid crystal display panel, and cholesteric liquid crystal comprises two stable states with different rotation directions and can reflect light with different rotation directions. The cholesteric liquid crystal display panel which is high in reflectivity, high in contrast ratio and good in stability and can be applied to reflection in an electric field regulation full-spectrum range can be obtained by adopting a strategy of regulating the rotation direction of the cholesteric liquid crystal through light and regulating the reflection wave band through an electric field.

Description

Chiral photosensitive molecular switch, cholesteric liquid crystal composition and display panel and preparation method thereof Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to a chiral photosensitive molecular switch, a cholesteric liquid crystal composition, a display panel, and a preparation method thereof. Background Art

[0002] Cholesteric liquid crystals (LCs) possess a unique helical structure and are extremely sensitive to a variety of external stimuli (electric and magnetic fields, light, temperature, humidity, pH, and mechanical forces). Therefore, they hold broad application prospects in fields such as dynamic displays, sensors, and tunable optical lasers, and have attracted widespread attention from researchers. Among them, oblique heliconic cholesteric (ChOH) LCs, a special type of cholesteric LC, exhibit a helical pitch that decreases with increasing electric field intensity within a certain range. This allows for selective reflection across a wide spectral range from the ultraviolet to the near-infrared. This makes oblique heliconic cholesteric LC materials exhibit great potential for applications in full-color reflective displays, smart windows, tunable filters, and holography. However, due to their unique molecular arrangement, the reflectivity of oblique heliconic cholesteric LC materials under electric field control is relatively low at normal viewing angles, resulting in low brightness in liquid crystal devices, which to some extent limits their practical applications.

[0003] How to optimize the tilted helical cholesteric liquid crystal material and ensure that the tilted helical cholesteric liquid crystal material has high reflectivity, high contrast and good stability is one of the important research topics for researchers.

[0004] The above information disclosed in this section is only for understanding the background of the inventive concept of the present disclosure and therefore the above information may contain information that does not constitute prior art.

[0005] Summary of the Invention

[0006] In one aspect, a chiral photosensitive molecular switch is provided, wherein the chemical structure of the chiral photosensitive molecular switch is shown in the following general formula I:

[0007] Among them, M1 is selected from The groups of the structure shown in the figure; the groups R1 and R2 are the same or different and include a benzene ring, a biphenyl ring, an aromatic ring or an aromatic heterocycle; L1 and L2 include C1 to C 10 of alkyl.

[0008] According to some exemplary embodiments, the chemical structure of at least one of the groups R1 and R2 is shown in one of the following formulae: or,

[0009] According to some exemplary embodiments, the chemical structure of the chiral photosensitive molecular switch is shown in one of the following formulas: or,

[0010] In another aspect, a cholesteric liquid crystal composition is provided, wherein the composition comprises the chiral photosensitive molecular switch as described in any one of the above items.

[0011] According to some exemplary embodiments, the composition further comprises a bent molecule mixture, a rod-shaped single crystal mixture, and a non-photosensitive chiral dopant.

[0012] According to some exemplary embodiments, based on the weight of the cholesteric liquid crystal composition, the chiral photosensitive molecular switch accounts for 0.5% to 10%.

[0013] According to some exemplary embodiments, based on the weight of the cholesteric liquid crystal composition, the non-photosensitive chiral dopant accounts for 0.5% to 10%.

[0014] According to some exemplary embodiments, based on the weight of the cholesteric liquid crystal composition, the bent molecule mixture accounts for 30% to 70%, and / or the rod-shaped single crystal mixture accounts for 30% to 70%.

[0015] According to some exemplary embodiments, based on the weight of the cholesteric liquid crystal composition, the proportion of the bent molecular mixture is 30% to 70%, the proportion of the rod-shaped single crystal mixture is 30% to 70%, the proportion of the chiral photosensitive molecular switch is 5% to 10%, and the proportion of the non-photosensitive chiral dopant is 5% to 10%. The sum of the proportions of the bent molecular mixture, the rod-shaped single crystal mixture, the chiral photosensitive molecular switch and the non-photosensitive chiral dopant is 100%.

[0016] On the other hand, a cholesteric liquid crystal display panel is provided, wherein the display panel comprises: a first substrate and a second substrate arranged opposite to each other; and a cholesteric liquid crystal layer located between the first substrate and the second substrate, wherein the cholesteric liquid crystal layer comprises a cholesteric liquid crystal composition, and the cholesteric liquid crystal composition comprises the chiral photosensitive molecular switch as described in any one of the above items, or the cholesteric liquid crystal composition is a composition as described in any one of the above items.

[0017] According to some exemplary embodiments, the cholesteric liquid crystal layer includes a first cholesteric liquid crystal unit and a second cholesteric liquid crystal unit, the liquid crystal in the first cholesteric liquid crystal unit has a tilted spiral structure with a first handedness, and the liquid crystal in the second cholesteric liquid crystal unit has a tilted spiral structure with a second handedness, and the first handedness and the second handedness are opposite.

[0018] According to some exemplary embodiments, an absolute value of a helical twisting force of liquid crystal in the first cholesteric liquid crystal cell is substantially equal to an absolute value of a helical twisting force of liquid crystal in the second cholesteric liquid crystal cell.

[0019] According to some exemplary embodiments, the display panel further includes: a first electrode located on the first substrate and a second electrode located on the second substrate; the cholesteric liquid crystal layer is configured such that: as the voltage applied between the first electrode and the second electrode changes, the wavelength corresponding to the reflection peak of the cholesteric liquid crystal layer changes.

[0020] According to some exemplary embodiments, the cholesteric liquid crystal layer is configured as follows: in response to a first voltage applied between the first electrode and the second electrode, the reflection peak of the cholesteric liquid crystal layer corresponds to a first wavelength; in response to a second voltage applied between the first electrode and the second electrode, the reflection peak of the cholesteric liquid crystal layer corresponds to a second wavelength; in response to a third voltage applied between the first electrode and the second electrode, the reflection peak of the cholesteric liquid crystal layer corresponds to a third wavelength, wherein the first voltage, the second voltage and the third voltage are different from each other, and the first wavelength, the second wavelength and the third wavelength respectively correspond to visible light of different colors.

[0021] According to some exemplary embodiments, the cholesteric liquid crystal layer is configured such that as the voltage applied between the first electrode and the second electrode decreases, a wavelength corresponding to a reflection peak of the cholesteric liquid crystal layer increases.

[0022] According to some exemplary embodiments, the first voltage is higher than the second voltage, and the second voltage is higher than the third voltage; the first wavelength is shorter than the second wavelength, and the second wavelength is shorter than the third wavelength.

[0023] According to some exemplary embodiments, the first substrate and the second substrate form a receiving space, the cholesteric liquid crystal layer is located in the receiving space, and the orthographic projections of the first cholesteric liquid crystal unit and the second cholesteric liquid crystal unit on the first substrate are alternately distributed.

[0024] According to some exemplary embodiments, the display panel further includes a third substrate located between the first substrate and the second substrate, and the cholesteric liquid crystal layer includes: a first sub-cholesteric liquid crystal layer located between the first substrate and the third substrate; and a second sub-cholesteric liquid crystal layer located between the third substrate and the second substrate, the first sub-cholesteric liquid crystal layer includes the first cholesteric liquid crystal unit, and the second sub-cholesteric liquid crystal layer includes the second cholesteric liquid crystal unit.

[0025] On the other hand, a method for preparing a cholesteric liquid crystal display panel is provided, wherein the method comprises: providing a first substrate and a second substrate; forming a cholesteric liquid crystal layer between the first substrate and the second substrate, wherein the cholesteric liquid crystal layer comprises a cholesteric liquid crystal composition, and the cholesteric liquid crystal composition comprises the chiral photosensitive molecular switch as described in any one of the above items, or the cholesteric liquid crystal composition is a composition as described in any one of the above items.

[0026] According to some exemplary embodiments, forming a cholesteric liquid crystal layer between the first substrate and the second substrate includes: injecting the cholesteric liquid crystal composition into a receiving space formed between the first substrate and the second substrate; irradiating the cholesteric liquid crystal composition with light of a predetermined wavelength to form a first cholesteric liquid crystal unit and a second cholesteric liquid crystal unit in the cholesteric liquid crystal layer, wherein the liquid crystal in the first cholesteric liquid crystal unit has a tilted spiral structure with a first handedness, and the liquid crystal in the second cholesteric liquid crystal unit has a tilted spiral structure with a second handedness, and the first handedness and the second handedness are opposite.

[0027] According to some exemplary embodiments, forming a cholesteric liquid crystal layer between the first substrate and the second substrate includes: injecting the cholesteric liquid crystal composition into a receiving space formed between the first substrate and the second substrate; irradiating the cholesteric liquid crystal composition with a mask and light of a predetermined wavelength, wherein the rotational orientation of the liquid crystal in the cholesteric liquid crystal layer that is not exposed to the light of the predetermined wavelength remains unchanged to form a first cholesteric liquid crystal unit; and the rotational orientation of the liquid crystal in the cholesteric liquid crystal layer that is exposed to the light of the predetermined wavelength is reversed to form a second cholesteric liquid crystal unit.

[0028] According to some exemplary embodiments, forming a cholesteric liquid crystal layer between the first substrate and the second substrate includes: injecting the cholesteric liquid crystal composition into the accommodation space formed between the first substrate and the third substrate to form a first sub-cholesteric liquid crystal layer; injecting the cholesteric liquid crystal composition into the accommodation space formed between the third substrate and the second substrate to form a second sub-cholesteric liquid crystal layer; irradiating the second sub-cholesteric liquid crystal layer with light of a predetermined wavelength, so that the liquid crystal of the second sub-cholesteric liquid crystal layer is exposed to the light of the predetermined wavelength and undergoes a rotational flip to form a second cholesteric liquid crystal unit; the liquid crystal of the first sub-cholesteric liquid crystal layer is not exposed to the light of the predetermined wavelength and the rotational flip remains unchanged to form a first cholesteric liquid crystal unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other objects and advantages of the present disclosure will become apparent from the following description of the present disclosure with reference to the accompanying drawings, which will help to provide a comprehensive understanding of the present disclosure.

[0030] FIG1 is a chemical structural formula of a chiral photosensitive molecular switch according to some embodiments of the present disclosure;

[0031] 2A and 2B are schematic diagrams of two stable structures of tilted helical cholesteric liquid crystals according to some embodiments of the present disclosure;

[0032] FIG3 is a schematic diagram of the preparation process of a chiral photosensitive molecular switch according to some embodiments of the present disclosure;

[0033] FIG4 is a schematic structural diagram of a cholesteric liquid crystal display panel according to some embodiments of the present disclosure;

[0034] FIG5 is a schematic diagram showing a comparison of the structures of a cholesteric liquid crystal display panel before and after illumination according to some embodiments of the present disclosure;

[0035] FIG6 is a schematic structural diagram of a cholesteric liquid crystal display panel according to some embodiments of the present disclosure;

[0036] FIG7 is a schematic diagram comparing the helical twisting forces of different states of a tilted helical cholesteric liquid crystal system to which a chiral photosensitive molecular switch is added according to some embodiments of the present disclosure;

[0037] FIG8 is a schematic diagram showing the relationship between the reflection peak and the applied voltage of a cholesteric liquid crystal display panel according to some embodiments of the present disclosure;

[0038] FIG9 is a schematic diagram of a stacked structure of a cholesteric liquid crystal display panel according to some embodiments of the present disclosure;

[0039] FIG10 is a flow chart of manufacturing a cholesteric liquid crystal display panel according to some embodiments of the present disclosure;

[0040] 11 is a flow chart of forming a cholesteric liquid crystal layer between the first substrate and the second substrate in step S2 in FIG. 10 ;

[0041] FIG12 is a schematic diagram of illumination during preparation in step S22 according to some embodiments of the present disclosure;

[0042] FIG13 is a schematic diagram of illumination during the preparation of step S22 according to other embodiments of the present disclosure. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0044] It should be noted that in the drawings, the sizes and relative sizes of elements may be exaggerated for clarity and / or descriptive purposes. Thus, the sizes and relative sizes of the individual elements are not necessarily limited to those shown in the drawings. In the specification and drawings, the same or similar reference numerals indicate the same or similar parts.

[0045] When an element is described as being "on" another element, "connected to" another element, or "bound to" another element, the element may be directly on the other element, directly connected to the other element, or directly bound to the other element, or there may be an intermediate element. However, when an element is described as being "directly on" another element, "directly connected to" another element, or "directly bound to" another element, there is no intermediate element. Other terms and / or expressions used to describe the relationship between elements should be interpreted in a similar manner, for example, "between" versus "directly between", "adjacent" versus "directly adjacent", or "on" versus "directly on", etc. In addition, the term "connected" may refer to a physical connection, an electrical connection, a communication connection, and / or a fluid connection. In addition, the X-axis, Y-axis, and Z-axis are not limited to the three axes of a rectangular coordinate system, and may be interpreted in a broader sense. For example, the X-axis, Y-axis, and Z-axis may be perpendicular to each other, or may represent different directions that are not perpendicular to each other. For the purposes of this disclosure, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be interpreted as only X, only Y, only Z, or any combination of two or more of X, Y, and Z, such as XYZ, XYY, YZ, and ZZ. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0046] It should be noted that although the terms "first," "second," etc. may be used herein to describe various parts, components, elements, regions, layers, and / or portions, these parts, components, elements, regions, layers, and / or portions should not be limited by these terms. Rather, these terms are used to distinguish one part, component, element, region, layer, and / or portion from another. Thus, for example, the first part, first member, first element, first region, first layer, and / or first portion discussed below may be referred to as a second part, second member, second element, second region, second layer, and / or second portion without departing from the teachings of the present disclosure.

[0047] For ease of description, spatially relative terms, such as "upper," "lower," "left," "right," etc., may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features.

[0048] As used herein, the terms "substantially," "about," "approximately," "roughly," and other similar terms are used as terms of approximation rather than as terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that would be recognized by one of ordinary skill in the art. To account for factors such as process fluctuations, measurement problems, and errors associated with the measurement of a particular quantity (i.e., limitations of the measurement system), "about" or "approximately" as used herein are inclusive of the stated value and mean within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art. For example, "approximately" can mean within one or more standard deviations, or within ±30%, ±20%, ±10%, ±5% of the stated value.

[0049] Chiral additives are an essential component of cholesteric liquid crystal materials, inducing a transition from the nematic phase to the cholesteric phase. Chiral additives include a class of molecules with unique properties: two stable states, each capable of transitioning between them under external field stimulation. This not only induces a transition from the nematic phase to the cholesteric phase, causing the nematic phase molecules to self-assemble into a helical structure, but also allows for the regulation of the cholesteric liquid crystal's helical pitch and reflection wavelength under external field stimulation. Chiral additives with this unique property are called chiral molecular switches. Chiral molecular switches can switch between stable states under external stimulation.

[0050] Chiral molecular switches must meet several requirements: 1. The existence of at least two stable states. 2. A switching method that allows the molecule to transition from one stable state to another. 3. A method for detecting the different stable states. Based on the stimulation method, molecular switches can be categorized as: light-controlled, electrically controlled, magnetically controlled, pressure-controlled, and thermally controlled. Light control has attracted widespread attention from researchers due to its inherent advantages. Currently, chiral molecules used to prepare photoresponsive cholesteric liquid crystals primarily include azobenzenes, diarylethenes, molecular motors, and α-cyano-substituted diarylethenes. Existing photoresponsive chiral molecules each have their own unique characteristics: azobenzene-based chiral molecules exhibit significant helical twisting forces, but the cis-isomer of azobenzene exhibits poor thermal stability and is prone to thermal relaxation. Furthermore, chiral molecules based on azobenzenes must be exposed to ultraviolet light to manipulate the helical pitch of the cholesteric phase. However, ultraviolet light is harmful to organisms, which limits the practical application of photoresponsive cholesteric liquid crystals. Diarylethenes-type chiral molecules have good thermal stability, but the spatial configuration of diarylethenes does not change much before and after the isomerization reaction, so under normal circumstances, the helical twisting force of this type of chiral molecules changes little. The helical twisting force of molecular motor-type chiral molecules can undergo large changes, but their light regulation process is often irreversible and can only be recovered through thermal relaxation. α-cyano-substituted diarylethenes is a photosensitive molecule with a π-conjugated group. Under the stimulation of light source, α-cyano-substituted diarylethenes can undergo Z / E isomerization. After connecting the chiral unit, the helical twisting force of the chiral photosensitive molecule can be changed. The cholesteric liquid crystal prepared by adding α-cyano-substituted diarylethenes chiral photosensitive molecular switches can exhibit good photoresponsive properties to light sources in a specific band, ultimately causing the reflected color of the cholesteric liquid crystal to change and exhibit good thermal stability.

[0051] Due to its unique optical rotation, circularly polarized light dichroism, and selective Bragg reflection properties, cholesteric liquid crystals have shown broad application prospects in optical materials. However, conventional cholesteric liquid crystals can only achieve the control of a single reflected color or the control of the scattering state by adjusting the voltage. Compared with traditional cholesteric liquid crystals, the greatest advantage of tilted helical cholesteric (ChOH) liquid crystal materials is that their pitch, tilt angle, and molecular chirality can be changed under external field stimulation such as an electric field, thereby achieving selective reflection across a wide spectral range from ultraviolet to near-infrared. Therefore, tilted helical cholesteric liquid crystal materials have more advantages than ordinary cholesteric materials in electric field control of reflected color. People can use a single tilted helical cholesteric liquid crystal device to achieve selective reflection of light from ultraviolet light to visible light and then to infrared light by simply applying an external electric field.

[0052] However, under natural light, due to the characteristics of its own tilted spiral structure, the reflectivity of the tilted spiral cholesteric liquid crystal material at a normal viewing angle is low. Correspondingly, the display contrast of the resulting liquid crystal device is low, which to some extent affects its possibility of practical application. Therefore, it is necessary to find a tilted spiral cholesteric liquid crystal material that can achieve high reflectivity and high contrast.

[0053] The inventors have discovered that by adding a chiral photosensitive molecular switch to a tilted helical cholesteric liquid crystal material, using light to control the rotational direction of the tilted helical cholesteric liquid crystal, and an electric field to control the reflection band, a tilted helical cholesteric liquid crystal device with high reflectivity, high contrast, and good stability can be obtained, which can be used for electric field control of reflection within the full spectrum.

[0054] FIG1 is a chemical structural formula of a chiral photosensitive molecular switch according to some embodiments of the present disclosure.

[0055] Some embodiments of the present disclosure provide at least one chiral photosensitive molecular switch, referring to FIG1 , wherein the chemical structure of the chiral photosensitive molecular switch is shown in the following general formula I:

[0056] Among them, M1 is selected from The group of the structure shown; the groups R1 and R2 are the same or different, and respectively include a benzene ring, a biphenyl ring, an aromatic ring or an aromatic heterocycle; L1 and L2 respectively include a C1~C10 alkyl group.

[0057] It should be noted that in each general formula herein, the substitution position of the group CN(H) representing the -CN group can be on one C of the double bond or on the other C of the double bond. For example, in the general formula, two groups CN(H) connected at both ends of a double bond indicate that the substitution position of the -CN group can be on either C of the double bond.

[0058] By adding a chiral photosensitive molecular switch to a tilted helical cholesteric liquid crystal, the tilted helical cholesteric liquid crystal can be controlled by both electric fields and light. After adding the chiral photosensitive molecular switch, the tilted helical cholesteric liquid crystal can be controlled by light to switch from one stable state to another. For example, the tilted helical cholesteric liquid crystal has two stable states: a left-handed tilted helical cholesteric phase and a right-handed tilted helical cholesteric phase. Assuming the initial state of the tilted helical cholesteric liquid crystal is the right-handed tilted helical cholesteric phase, upon exposure to light of a specific wavelength, the tilted helical cholesteric liquid crystal can switch to the left-handed tilted helical cholesteric phase. By designing the illumination range, a portion of the tilted helical cholesteric liquid crystal can be illuminated to switch from the right-handed tilted helical cholesteric phase to the left-handed tilted helical cholesteric phase, while the remaining portion, unexposed, remains in the right-handed tilted helical cholesteric phase. This allows the formation of both left-handed and right-handed tilted helical cholesteric phases within the tilted helical cholesteric liquid crystal, enabling simultaneous reflection of both left-handed and right-handed light, significantly improving the reflective contrast of the tilted helical cholesteric liquid crystal.

[0059] 2A and 2B are schematic diagrams of two stable structures of tilted helical cholesteric liquid crystals according to some embodiments of the present disclosure.

[0060] For example, in some embodiments of the present disclosure, with reference to FIG2A and FIG2B , the tilted helical cholesteric liquid crystal D may include a right-handed tilted helical cholesteric liquid crystal D1 and a left-handed tilted helical cholesteric liquid crystal D2. For example, the initial state of the tilted helical cholesteric liquid crystal D to which a chiral photosensitive molecular switch is added may include the right-handed tilted helical cholesteric liquid crystal D1. After being irradiated with light of a specific wavelength, such as light of 365 nm or light of 450 nm, the steady state of the tilted helical cholesteric liquid crystal D may be transformed from the right-handed tilted helical cholesteric liquid crystal D1 to the left-handed tilted helical cholesteric liquid crystal D2. The chiral photosensitive molecular switch added to the tilted helical cholesteric liquid crystal has a small helical twisting force (HTP) value in the initial state. When the tilted helical cholesteric liquid crystal is irradiated with light of different wavelengths, the helical twisting force of the chiral photosensitive molecule increases sharply and significantly. Due to its excellent helical twisting force changes in the initial state and after light stimulation, introducing a small amount of this chiral photosensitive molecular switch into the tilted helical cholesteric liquid crystal system can be used together with other non-photosensitive chiral dopants to regulate the pitch of the tilted helical cholesteric liquid crystal system, thereby causing the chirality of the tilted helical cholesteric liquid crystal system to flip between left-handed and right-handed after light irradiation.

[0061] The helical twisting force of a chiral photosensitive molecular switch changes differently under different wavelengths of light. For example, the helical twisting force of a chiral photosensitive molecular switch under 450nm wavelength light is greater than that under 365nm wavelength light. The greater the change in helical twisting force, the more favorable it is for the chirality flip of the tilted helical cholesteric liquid crystal system.

[0062] For example, in some embodiments of the present disclosure, the chiral photosensitive molecular switch can be an α-cyano-substituted diarylethene molecule, which has a π-conjugated group and good photosensitivity. Under the stimulation of external light source, Z / E isomerization can occur. When it is connected to a chiral unit, it can change the helical twisting force of the chiral photosensitive molecule, thereby enabling the cholesteric liquid crystal prepared by introducing the α-cyano-substituted diarylethene chiral photosensitive molecular switch to exhibit good photoresponsive properties to light sources of a specific wavelength band, ultimately causing the cholesteric liquid crystal reflective color to change and having good thermal stability.

[0063] For example, in some embodiments of the present disclosure, chiral photosensitive molecular switches with different functional groups have different changes in their helical twisting force after illumination, and therefore have different effects on the steady-state transition of the tilted helical cholesteric phase liquid crystal to which the chiral photosensitive molecular switch is added.

[0064] For example, in a chiral photosensitive molecular switch having a chemical structure of general formula I, when other functional group structures are the same,

[0065] Wherein M1 is When the structure is in the same illumination condition, the variation of the spiral twisting force is greater than that of the structure in which M1 is The change in the helical twisting force under the same lighting conditions when the structure is changed.

[0066] When the helical twisting force of the chiral photosensitive molecular switch is greater under light conditions, it is more conducive to the chirality reversal of the tilted helical cholesteric phase liquid crystal to which the chiral photosensitive molecular switch is added.

[0067] For example, in some embodiments of the present disclosure, the chemical structure of at least one of the groups R1 and R2 in the chiral photosensitive molecular switch is as shown in one of the following formulae: or,

[0068] Wherein, R1 and R2 may be the same or different. R1 and R2 groups may be benzene rings, biphenyl rings, aromatic rings or aromatic heterocycles.

[0069] The R1 and R2 groups can make chiral photosensors both chiral and photoresponsive. The introduction of R1 and R2 groups can increase the degree of conjugation of the molecule, thereby imparting controllable photoresponsive properties. For example, the R1 or R2 groups can contain various groups such as -CN, -N, -S, or -O. These groups affect the degree of conjugation of the R1 or R2 groups. As the degree of conjugation increases, the sensitivity will red-shift. In other words, when the degree of conjugation in the chiral photosensor is higher, the wavelength of the irradiated light required to trigger its photosensitivity change will increase.

[0070] FIG3 is a schematic diagram of the preparation process of a chiral photosensitive molecular switch according to some embodiments of the present disclosure.

[0071] For example, in some embodiments of the present disclosure, the chemical structure of the chiral photosensitive molecular switch may be shown as one of the following formulae: or,

[0072] For the convenience of description, the chiral photosensitive molecular switches with the above four structures are respectively referred to as Switch 1, Switch 2, Switch 3 and Switch 4.

[0073] For example, in some embodiments of the present disclosure, referring to FIG. 3 , the manufacturing process of Switch 4 may include the following steps S01-S06:

[0074] In step S01, intermediate product (S)-2 is formed by dissolving 6,6'-dibromo-[1,1'-binaphthyl]-2,2'-diol in anhydrous acetonitrile. Once fully dissolved, bromooctane and potassium carbonate are weighed and added sequentially to a flask, and the mixture is refluxed at 80°C for 24 hours. After the reaction is completed, the crude product is subjected to primary purification through extraction, washing, and drying. It is further purified and separated using a chromatographic column and dried to obtain intermediate product (S)-2.

[0075] In step S02, intermediate product (S)-3 is formed by dissolving compound (S)-2 and previously prepared sodium 2-cyanoacetate in 65 ml of anhydrous xylene. Allylpalladium chloride dimer and 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene are sequentially added to the mixture, and the mixture is stirred and refluxed at high temperature in the absence of oxygen for 8 hours. The mixture is then cooled and filtered under reduced pressure. The resulting filtrate is concentrated, and the crude product is purified by column chromatography to obtain the intermediate product as a yellow oil.

[0076] In step S03, intermediate product 3 is formed by weighing 5-bromo-2-thiophenecarboxaldehyde and 4-methoxyphenylboronic acid pinacol ester and stirring and dissolving them in an appropriate amount of toluene. Tetrakis(triphenylphosphine)palladium catalyst, n-propanol, and a 20wt% sodium carbonate solution are then added sequentially. The mixture is refluxed at high temperature under nitrogen protection. After the reaction, the crude product is initially purified by extraction, washing, drying, and concentration, followed by fine purification using column chromatography, spin-dried, and vacuum-dried at room temperature for 3 hours to obtain a pure white solid.

[0077] In step S04, intermediate product 4 is formed by weighing 5-bromo-2-thiophenecarboxaldehyde and 4-(N,N-dimethylamino)phenylboronic acid pinacol ester and stirring and dissolving them in an appropriate amount of toluene. Tetrakis(triphenylphosphine)palladium catalyst, n-propanol, and a 20wt% sodium carbonate solution are then added in sequence. The mixture is refluxed at high temperature under nitrogen protection. After the reaction is completed, the crude product is initially purified by extraction, washing, drying, and concentration, and then finely purified by column chromatography, spin-dried, and vacuum-dried at room temperature for 3 hours to obtain a pure white solid.

[0078] In step S05, intermediate product 5 is formed by weighing 5-bromo-2-thiophenecarboxaldehyde and 4-cyanophenylboronic acid pinacol ester and stirring and dissolving them in an appropriate amount of toluene. Tetrakis(triphenylphosphine)palladium catalyst, n-propanol, and a 20 wt% sodium carbonate solution are then added sequentially. The mixture is refluxed at high temperature under nitrogen protection. After the reaction, the crude product is initially purified by extraction, washing, drying, and concentration, followed by fine purification using column chromatography, spin-dried, and vacuum-dried at room temperature for 3 hours to obtain a pure white solid.

[0079] In step S06, Switch 4 is formed by dissolving intermediate (S)-3 and intermediate 5 in anhydrous THF at a molar ratio of 1:2.5, and then slowly adding potassium tert-butoxide with stirring. The mixture is refluxed at 60°C. A dilute HCl solution is then added to the mixture to quench the reaction and adjust the pH to neutral. The crude product is subjected to a simple primary purification and then finely purified by column chromatography to obtain the desired product. The entire synthesis process must be carried out in the dark. Approximately 2.0 g of solid is finally obtained.

[0080] For example, in some embodiments of the present disclosure, the preparation method of Switch 1 can be to dissolve the intermediate product (S)-3 in the above-mentioned step S02 and the intermediate product 3 in the step S03 in anhydrous THF at a molar ratio of 1:1, and then slowly add potassium tert-butoxide while stirring. The mixture is refluxed at 60°C. Thereafter, a dilute HCl solution is added to the above mixture to quench the reaction and adjust the pH to neutral. The obtained crude product is first subjected to a simple primary purification and then finely purified by column chromatography to finally obtain the target product. The entire synthesis process needs to be carried out in the dark.

[0081] For example, in some embodiments of the present disclosure, the preparation method of Switch 2 can be to dissolve the intermediate product (S)-3 in the above-mentioned step S02 and the intermediate product 4 in the step S04 in anhydrous THF at a molar ratio of 1:2.5, and then slowly add potassium tert-butoxide while stirring. The mixture is refluxed at 60°C. Thereafter, a dilute HCl solution is added to the above mixture to quench the reaction and adjust the pH to neutral. The obtained crude product is first subjected to a simple primary purification and then finely purified by column chromatography to finally obtain the target product. The entire synthesis process needs to be carried out in the dark.

[0082] For example, in some embodiments of the present disclosure, the preparation method of Switch 3 can be to dissolve the intermediate product (S)-3 in the above-mentioned step S02 and the intermediate product 5 in the step S05 in anhydrous THF at a molar ratio of 1:1, and then slowly add potassium tert-butoxide while stirring. The mixture is refluxed at 60°C. Thereafter, a dilute HCl solution is added to the above mixture to quench the reaction and adjust the pH to neutral. The obtained crude product is first subjected to a simple primary purification and then finely purified by column chromatography to finally obtain the target product. The entire synthesis process needs to be carried out in the dark.

[0083] For example, in some embodiments of the present disclosure, the chiral photosensitive molecular switch may be Switch 4, which exhibits rapid light control and excellent stability. The addition of Switch 4 allows the tilted helical cholesteric liquid crystal to rapidly flip its chirality under illumination, facilitating the fabrication of tilted helical cholesteric liquid crystal display panels.

[0084] Illustratively, at least some embodiments of the present disclosure further provide a cholesteric liquid crystal composition, wherein the composition may include the chiral photosensitive molecular switch as described above, for example, the composition may include at least one of Switch 1, Switch 2, Switch 3, or Switch 4.

[0085] As shown in Table 1 below, the chiral photosensitive molecular switch structure and its hydrogen spectrum data according to some embodiments of the present disclosure are exemplified.

[0086] Table 1 Chiral photosensitive molecular switch structure and its hydrogen spectrum data

[0087] Illustratively, in some embodiments of the present disclosure, the composition may further include a bent molecule mixture, a rod-shaped single crystal mixture, and a non-photosensitive chiral dopant.

[0088] The cholesteric liquid crystal composition can be obtained by uniformly mixing the bent molecular mixture, the rod-shaped single crystal molecular mixture, the non-photosensitive chiral dopant, and the chiral photosensitive molecular switch in the presence of an organic solvent, and then evaporating the solvent to obtain the cholesteric liquid crystal composition. The organic solvent can include at least one of acetone, methanol, ethanol, tetrahydrofuran, dichloromethane, and chloroform.

[0089] For example, in some embodiments of the present disclosure, the chiral photosensitive molecular switch accounts for 0.5% to 10% by weight of the cholesteric liquid crystal composition.

[0090] For example, in some embodiments of the present disclosure, the chiral photosensitive molecular switch may include at least one of Switch 1, Switch 2, Switch 3, or Switch 4.

[0091] For example, in some embodiments of the present disclosure, the non-photosensitive chiral dopant accounts for 0.5% to 10% by weight of the cholesteric liquid crystal composition. For example, the non-photosensitive chiral dopant may include at least one of S811, R811, S5011, and R5011.

[0092] Among them, the molecular structure of S811 is as follows:

[0093] The molecular structure of R811 is as follows:

[0094] The molecular structure of S5011 is as follows:

[0095] The molecular structure of R5011 is as follows:

[0096] For example, in some embodiments of the present disclosure, based on the weight of the cholesteric liquid crystal composition, the bent molecular mixture accounts for 30% to 70%, and / or the rod-shaped single crystal mixture accounts for 30% to 70%.

[0097] The bent molecular mixture can be a mixture of compound 1, compound 2 and compound 3, wherein:

[0098] The molecular structure of compound 1 is as follows:

[0099] The molecular structure of compound 2 is as follows:

[0100] The molecular structure of compound 3 is as follows:

[0101] For example, based on the total weight of the curved molecular mixture, the content of compound 1 is 77%, the content of compound 2 is 13%, and the content of compound 3 is 10%. By mixing compound 1, compound 2 and compound 3 in proportion, a curved molecular mixture that can induce tilted helical cholesteric liquid crystal material can be obtained.

[0102] As shown in Table 2 below, the compound structures and hydrogen spectrum data according to some embodiments of the present disclosure are exemplified.

[0103] Table 2 Compound structures and their H spectral data

[0104] Exemplarily, the rod-shaped single crystal mixture may be a mixture of single crystal molecules 1 and single crystal molecules 2, wherein:

[0105] The molecular structure of single crystal molecule 1 is as follows:

[0106] The molecular structure of single crystal molecule 2 is as follows:

[0107] For example, based on the total weight of the single crystal molecule mixture, the content of single crystal molecule 1 is 84%, and the content of single crystal molecule 2 is 16%. The single crystal molecule mixture can be obtained by mixing single crystal molecule 1 and single crystal molecule 2 in proportion.

[0108] In the presence of an organic solvent, the above-mentioned bent molecular mixture, rod-shaped single crystal molecular mixture, non-photosensitive chiral dopant and chiral photosensitive molecular switch are mixed uniformly in a certain proportion, and the solvent is evaporated to obtain a cholesteric liquid crystal composition with electrically induced tilted helix.

[0109] In some preferred embodiments, based on the weight of the cholesteric liquid crystal composition, the proportion of the bent molecular mixture is 30% to 70%, the proportion of the rod-shaped single crystal mixture is 30% to 70%, the proportion of the chiral photosensitivity molecular switch is 5% to 10%, and the proportion of the non-photosensitive chiral dopant is 5% to 10%. The sum of the proportions of the bent molecular mixture, the rod-shaped single crystal mixture, the chiral photosensitivity molecular switch and the non-photosensitive chiral dopant is 100%.

[0110] For example, the above-mentioned bent molecular mixture, rod-shaped single crystal molecular mixture, non-photosensitive chiral dopant and chiral photosensitive molecular switch are mixed in a weight ratio of 50:40:5:5 respectively, and after evaporating the solvent, a cholesteric liquid crystal composition in which a tilted spiral can be induced by electrical application is obtained.

[0111] Table 3 shows the experimental performance of cholesteric liquid crystal compositions under different ratios. In Table 3, "Liquid Crystal 1" and "Liquid Crystal 2" respectively represent mixtures of rod-shaped single crystal molecules of different structures or ratios. For example, they can be mixtures of different ratios of the above-mentioned single crystal molecules 1 and single crystal molecules 2, respectively. The values ​​under each column of "Liquid Crystal 1", "Liquid Crystal 2", "Bent Molecular Mixture", "Chiral Dopant", and "Switch 4" respectively represent the weight percentages of the corresponding substances in the cholesteric liquid crystal composition. It can be seen from the experimental performance in Table 3 that the experimental performance of Group 3 is better, that is, based on the weight of the cholesteric liquid crystal composition, the proportion of the bent molecular mixture is 50%, the proportion of the rod-shaped single crystal mixture is 40%, the proportion of the chiral photosensitive molecular switch is 5%, and the proportion of the non-photosensitive chiral dopant is 5%. The following experimental phenomena were observed: data and inversion can be measured, and the results are repeated many times, all with excellent reflection performance.

[0112] Table 3 Experimental performance of cholesteric liquid crystal compositions at different ratios

[0113] Illustratively, a cholesteric liquid crystal composition that can induce a tilted spiral upon application of electricity can use light to regulate the rotational direction of the tilted spiral cholesteric liquid crystal, and an electric field to regulate the reflection band, and can be used to prepare a tilted spiral cholesteric liquid crystal with high reflectivity, high contrast, and good stability that can be used for electric field regulation of reflection within the full spectrum range.

[0114] Furthermore, the cholesteric liquid crystal composition capable of inducing tilted helices upon application of electricity can be used to prepare cholesteric liquid crystal display panels with high reflectivity and high contrast. Within a certain range, the higher the chiral agent content in the cholesteric liquid crystal composition, the higher the reflective contrast and better the display quality of the cholesteric liquid crystal display panel prepared using the cholesteric liquid crystal composition.

[0115] FIG4 is a schematic structural diagram of a cholesteric liquid crystal display panel according to some embodiments of the present disclosure.

[0116] Referring to FIG4 , at least some embodiments of the present disclosure further provide a cholesteric liquid crystal display panel, wherein the display panel 100 comprises: a first substrate 1 and a second substrate 2 disposed opposite each other; and a cholesteric liquid crystal layer 3 located between the first substrate 1 and the second substrate 2, wherein the cholesteric liquid crystal layer 3 comprises a cholesteric liquid crystal composition, wherein the cholesteric liquid crystal composition comprises the chiral photosensitive molecular switch described above, or the cholesteric liquid crystal composition is the composition described above. Because the cholesteric liquid crystal composition contains the chiral photosensitive molecular switch, it can undergo photoisomerization under light control, achieving chirality flipping.

[0117] For example, referring to FIG. 4 , the cholesteric liquid crystal layer 3 may include tilted helical cholesteric liquid crystal D. The tilted helical cholesteric liquid crystal D may be obtained by injecting a cholesteric liquid crystal composition into a conductive liquid crystal cell at a certain temperature, cooling the temperature to room temperature at a certain rate, applying an external voltage to cause the cholesteric liquid crystal in the liquid crystal cell to enter a homeotropic state, and then reducing the voltage to obtain the tilted helical arrangement of the cholesteric liquid crystal. For example, the cooling rate may be 0.5-3°C / min, and the applied voltage may be 75-100V.

[0118] FIG5 is a schematic diagram showing a comparison of the structures of a cholesteric liquid crystal display panel before and after illumination according to some embodiments of the present disclosure.

[0119] For example, in some embodiments of the present disclosure, referring to FIG5 , before the cholesteric liquid crystal display panel is irradiated with light, the cholesteric liquid crystal layer 3 may include a right-handed tilted spiral cholesteric liquid crystal D1. When the cholesteric liquid crystal layer 3 is irradiated with light of a specific wavelength band, the cholesteric liquid crystal layer 3 undergoes a chirality flip due to the presence of a chiral photosensitive molecular switch in the cholesteric liquid crystal layer 3 causing photoinduced structural alienation, wherein the right-handed tilted spiral cholesteric liquid crystal D1 is transformed into a left-handed tilted spiral cholesteric liquid crystal D2.

[0120] Illumination can flip the chirality of the tilted helical cholesteric liquid crystal D, achieving a transition from right-handed tilted helical cholesteric liquid crystal D1 to left-handed tilted helical cholesteric liquid crystal D2, which then remains stable. Furthermore, by designing the illumination range, a portion of the tilted helical cholesteric liquid crystal exposed to illumination can transform from the right-handed tilted helical cholesteric phase to the left-handed tilted helical cholesteric phase, while the remaining portion unexposed to illumination remains in the right-handed tilted helical cholesteric phase. This allows the formation of both left-handed and right-handed tilted helical cholesteric liquid crystals within the tilted helical cholesteric liquid crystal D, enabling simultaneous reflection of both left-handed and right-handed light, significantly improving the reflective contrast of the tilted helical cholesteric liquid crystal.

[0121] FIG6 is a schematic structural diagram of a cholesteric liquid crystal display panel according to some embodiments of the present disclosure.

[0122] For example, in some embodiments of the present disclosure, referring to FIG6 , the cholesteric liquid crystal layer 3 includes a first cholesteric liquid crystal cell 31 and a second cholesteric liquid crystal cell 32. The liquid crystal in the first cholesteric liquid crystal cell 31 has a tilted helical structure with a first handedness, and the liquid crystal in the second cholesteric liquid crystal cell 32 has a tilted helical structure with a second handedness, where the first handedness and the second handedness are opposite. For example, the first handedness can be left-handed, and the corresponding second handedness can be right-handed; or, the first handedness can be right-handed, and the corresponding second handedness is left-handed. For example, a cholesteric liquid crystal display panel can include both left-handed tilted helical cholesteric liquid crystals and right-handed tilted helical cholesteric liquid crystals.

[0123] Since both left-handed and right-handed tilted helical cholesteric liquid crystals are formed in the cholesteric liquid crystal display panel, both left-handed and right-handed reflected light can be reflected simultaneously, thereby greatly improving the reflection contrast of the tilted helical cholesteric liquid crystal display panel.

[0124] FIG7 is a schematic diagram comparing the helical twisting forces in different states of a tilted helical cholesteric liquid crystal system to which a chiral photosensitive molecular switch is added according to some embodiments of the present disclosure.

[0125] 7 , FIG. 7 a ) and FIG. 7 b ) respectively show the Cano line changes and phase changes of the cholesteric liquid crystal system doped with Switch4 in different states observed under a polarizing microscope.

[0126] It should be noted that in the art, the Grandjean-Cano method can be used to determine the chirality of a molecule, i.e., its HTP value. For example, an appropriate amount of Switch 4 can be weighed and added to a liquid crystal host to prepare a 5wt% liquid crystal mixture. Dichloromethane is then added, ultrasonicated for 10 minutes to fully dissolve the mixture, and then dried in a vacuum oven. After drying, the mixture is poured into a wedge-type liquid crystal cell at room temperature. The changes in the Cano lines of each photostable state are observed under a polarizing microscope, and the Cano line spacing is recorded.

[0127] In the embodiments of the present disclosure, the chiral light control performance can be quantitatively analyzed by calculating the HTP value of the liquid crystal system in various states.

[0128] As shown in the leftmost portion of Figure 7 (a), in the initial state, the HTP value can be calculated from the spacing of the Cano lines to be +11.65. The liquid crystal system was poured into a 10μm thick vertically aligned liquid crystal cell and observed under a polarizing microscope. As shown in the leftmost portion of Figure 7 (b), the typical cholesteric fingerprint texture can be clearly seen. According to the HTP value and CD test results, it can be seen that Switch 4 induces a left-handed helical structure at this time.

[0129] The Switch 4 molecule is very sensitive to 365nm and 450nm light sources. In the initial state, irradiation with 365nm or 450nm light source for 30 seconds will cause the molecule to isomerize to PSS. 365 or PSS 450 state.

[0130] Figure 7 a) and b) in the middle and rightmost sides show the transition of the liquid crystal system from the initial state to the PSS state. 450 Cano line changes and phase changes during the state process. 450The Carnot lines gradually disappear from the initial state, see the middle figure a) in Figure 7, HTP = 0; then the Carnot lines slowly reappear, forming new Carnot lines with wider spacing, see the right figure a) in Figure 7, HTP = -11.28; the phase state also shows the same phenomenon, the fingerprint texture first gradually disappears, see the middle figure b) in Figure 7, and then a new fingerprint texture with relatively sparse texture is formed, see the right figure b) in Figure 7. These phenomena fully demonstrate that the liquid crystal system has undergone phase transition and chirality reversal under the induction of blue light, which is due to the fact that in PSS 450 The chirality of the acceptor increases dramatically and exceeds the sum of the chirality of the two donors. Therefore, the chirality of the assembly is dominated by the acceptor part, thereby inducing a right-handed cholesteric helical structure.

[0131] The experimental data in Figure 7 show that Switch 4 has a fast light control rate and good stability. Moreover, the molecular chirality changes and can be stably present after light irradiation. By co-incorporating it into the system with a chiral agent of the opposite hand, it is easy to achieve a change between the initial state and PSS. 450 When the chirality is flipped, the absolute value of the HTP value of the system before and after the chirality flip is close.

[0132] Illustratively, in some embodiments of the present disclosure, the absolute value of the helical twisting force of the liquid crystal in the first cholesteric liquid crystal cell is substantially equal to the absolute value of the helical twisting force of the liquid crystal in the second cholesteric liquid crystal cell.

[0133] It should be noted that, in the text, when the phrase "the absolute values ​​of the helical twisting forces (i.e., HTP) are approximately equal or similar" is used, "approximately equal or similar" includes at least the following situations: the absolute values ​​of the two helical twisting forces (i.e., HTP) used for comparison are strictly equal; or, the ratio of the absolute values ​​of the two helical twisting forces (i.e., HTP) used for comparison is between 0.8 and 1.2.

[0134] For example, in some embodiments of the present disclosure, the chiral photosensitive molecular switch may be Switch 4, which is very sensitive to 365nm and 450nm light sources. In the initial state, the tilted helical cholesteric liquid crystal doped with the chiral photosensitive molecular switch is irradiated with a 365nm or 450nm light source for 30 seconds, and the liquid crystal undergoes isomerization to PSS. 365 or PSS 450 state, where PSS 365 It refers to the steady state of liquid crystal after the chirality is reversed under 365nm wavelength light. 450 It refers to the steady state of liquid crystal after the chirality is reversed under 450nm wavelength light.

[0135] After being irradiated with light of a specific wavelength, the chirality of the tilted helical cholesteric liquid crystal doped with the chiral photosensitive molecular switch changes and can be stably present after being irradiated. For example, referring to Figure 7, the chirality of the tilted helical cholesteric liquid crystal system can be easily achieved by co-incorporating the Switch 4 molecule and the opposite chiral agent into the tilted helical cholesteric liquid crystal system. 450 The chirality flip occurs between the states and the absolute value of the HTP value of the system before and after the chirality flip is close. For example, the absolute value of the HTP of the initial state is 11.65um-1, while the absolute value of the HTP of the PSS is 11.65um-1. 450 The absolute value of HTP in the first stable state is 11.28 μm-1, and the absolute values ​​of HTP in the two stable states before and after flipping are similar, which is conducive to the further design of tilted helical cholesteric liquid crystal display panels with high reflectivity.

[0136] For example, in some embodiments of the present disclosure, with continued reference to FIG. 6 , the display panel further includes: a first electrode 11 located on the first substrate 1; and a second electrode 21 located on the second substrate 2; the cholesteric liquid crystal layer 3 is configured such that the wavelength corresponding to the reflection peak of the cholesteric liquid crystal layer 3 changes as the voltage V applied between the first electrode 11 and the second electrode 21 changes. For example, the first electrode 11 and the second electrode 21 may be ITO transparent conductive electrodes, that is, the first substrate 1 and the second substrate 2 may be single-sided conductive substrates.

[0137] In some exemplary embodiments of the present disclosure, the bent molecules of the inducible tilted helix cholesteric liquid crystal material shown in Compound 1, Compound 2, and Compound 3 in Table 2 are mixed in dichloromethane to obtain the bent molecular mixture, for example, based on the total weight of the bent molecular mixture, the content of Compound 1 is 77%, the content of Compound 2 is 13%, and the content of Compound 3 is 10%; the above-mentioned single crystal molecule 1 and the above-mentioned single crystal molecule 2 are mixed to obtain the single crystal molecular mixture, for example, based on the total weight of the single crystal molecular mixture, the content of single crystal molecule 1 is 84%, and the content of single crystal molecule 2 is 16%; the above-mentioned bent molecular mixture, single crystal molecular mixture, non-photosensitive chiral dopant and chiral photosensitive molecular switch Switch 4 are mixed in a weight ratio of 40:50:5:5, respectively, and after evaporating the solvent, a cholesteric liquid crystal mixture inducible to tilted helix upon application of electricity is obtained. At elevated temperature, two samples were poured into a stacked liquid crystal cell constructed by laminating two planar-aligned, single-sided conductive ITO-coated glass substrates and one planar-aligned, double-sided conductive ITO-coated glass substrate (as shown in Figure 9). Alternatively, the cells were poured into a liquid crystal cell constructed by laminating two planar-aligned, single-sided conductive ITO-coated glass substrates (as shown in Figure 6). The temperature was then cooled to room temperature at a rate of 1-5°C / min. The prepared liquid crystal cells were then layered and illuminated with 450nm blue light (as shown in Figure 5) or through a mask (as shown in Figure 12). Exposure to light caused the chiral photoswitch molecules to change their configuration, resulting in a structural change in the chiral handedness of the liquid crystal system. An external electric field was used to induce a tilted helical arrangement of the cholesteric liquid crystal molecules (as shown in Figures 6 and 9). The reflected colors were first observed for both left-handed and right-handed rotations. Subsequently, the reflected colors were observed for both left-handed and right-handed rotations (as shown in Figure 8).

[0138] FIG8 is a schematic diagram showing the relationship between the reflection peak and the applied voltage of a cholesteric liquid crystal display panel according to some embodiments of the present disclosure. It should be noted that in FIG8 , the abscissa Wavelength (nm) represents the wavelength (nm), and the ordinate Reflectence (au) represents the reflected light intensity.

[0139] For example, in some embodiments of the present disclosure, with reference to FIG6 and FIG8 , the cholesteric liquid crystal layer 3 is configured such that: in response to a first voltage V1 applied between the first electrode 11 and the second electrode 21 , a reflection peak of the cholesteric liquid crystal layer 3 corresponds to a first wavelength λ1;

[0140] In response to a second voltage V2 applied between the first electrode 11 and the second electrode 21 , the reflection peak of the cholesteric liquid crystal layer 3 corresponds to a second wavelength λ2;

[0141] In response to the third voltage V3 applied between the first electrode 11 and the second electrode 21, the reflection peak of the cholesteric liquid crystal layer 3 corresponds to the third wavelength λ3.

[0142] The first voltage V1 , the second voltage V2 , and the third voltage V3 are different from each other, and the first wavelength λ1 , the second wavelength λ2 , and the third wavelength λ3 correspond to visible light of different colors, respectively.

[0143] For example, in some embodiments of the present disclosure, the cholesteric liquid crystal layer 3 is configured such that as the voltage V applied between the first electrode 11 and the second electrode 21 decreases, the wavelength corresponding to the reflection peak of the cholesteric liquid crystal layer increases.

[0144] Exemplarily, continuing to refer to Figures 6 and 8, the first voltage V1 may be greater than the second voltage V2, and accordingly, the first wavelength λ1 corresponding to the reflection peak of the cholesteric liquid crystal layer 3 in response to the first voltage V1 applied between the first electrode 11 and the second electrode 21 may be smaller than the second wavelength λ2 corresponding to the reflection peak of the cholesteric liquid crystal layer 3 in response to the second voltage V2 applied between the first electrode 11 and the second electrode 21; the second voltage V2 may be greater than the third voltage V3, and accordingly, the second wavelength λ2 corresponding to the reflection peak of the cholesteric liquid crystal layer 3 in response to the second voltage V2 applied between the first electrode 11 and the second electrode 21 may be smaller than the third wavelength λ3 corresponding to the reflection peak of the cholesteric liquid crystal layer 3 in response to the third voltage V3 applied between the first electrode 11 and the second electrode 21.

[0145] Exemplarily, the first voltage V1 may be 0.99V, the second voltage V2 may be 0.89V, the third voltage V3 may be 0.759V, the visible light corresponding to the first wavelength λ1 may be blue light, the visible light corresponding to the second wavelength λ2 may be green light, and the visible light corresponding to the third wavelength λ3 may be red light.

[0146] For example, in some embodiments of the present disclosure, with continued reference to FIG6 , the first substrate 1 and the second substrate 2 are aligned to form a housing space 4, the cholesteric liquid crystal layer 3 is located in the housing space 4, and the orthographic projections of the first cholesteric liquid crystal cells 31 and the second cholesteric liquid crystal cells 32 on the first substrate 1 are alternately distributed. The liquid crystal in the first cholesteric liquid crystal cell 31 has a tilted helical structure with a first handedness, and the liquid crystal in the second cholesteric liquid crystal cell 32 has a tilted helical structure with a second handedness, wherein the first handedness and the second handedness are opposite. For example, the first handedness can be left-handed, and the corresponding second handedness can be right-handed; or, the first handedness can be right-handed, and the corresponding second handedness is left-handed. In other words, the cholesteric liquid crystal display panel can include both left-handed tilted helical cholesteric liquid crystals and right-handed tilted helical cholesteric liquid crystals.

[0147] By forming both left-handed and right-handed tilted helical cholesteric phases in the cholesteric liquid crystal display panel, left-handed and right-handed reflected light can be reflected simultaneously, thereby significantly improving the reflection contrast of the tilted helical cholesteric liquid crystal.

[0148] The alternating distribution of the orthographic projections of the first cholesteric liquid crystal unit 31 and the second cholesteric liquid crystal unit 32 on the first substrate 1 can ensure that the intensity of the left-handed reflected light is approximately equal to the intensity of the right-handed reflected light, thereby ensuring that the brightness of the cholesteric liquid crystal display panel observed at different side positions is approximately the same, which can improve the display effect of the display panel.

[0149] FIG9 is a schematic diagram of a stacked structure of a cholesteric liquid crystal display panel according to some embodiments of the present disclosure.

[0150] For example, in some embodiments of the present disclosure, referring to FIG. 9 , the display panel 100 may further include a third substrate 5 positioned between the first substrate 1 and the second substrate 2. The cholesteric liquid crystal layer 3 includes: a first sub-cholesteric liquid crystal layer 301 positioned between the first substrate 1 and the third substrate 5; and a second sub-cholesteric liquid crystal layer 302 positioned between the third substrate 5 and the second substrate 2. The first sub-cholesteric liquid crystal layer 301 includes a first cholesteric liquid crystal cell 31, and the second sub-cholesteric liquid crystal layer 302 includes a second cholesteric liquid crystal cell 32. The liquid crystal in the first cholesteric liquid crystal cell 31 may have a tilted helical structure with a first handedness, and the liquid crystal in the second cholesteric liquid crystal cell 32 may have a tilted helical structure with a second handedness, with the first handedness and the second handedness being opposite. For example, the first handedness may be left-handed, and the corresponding second handedness may be right-handed; alternatively, the first handedness may be right-handed, and the corresponding second handedness may be left-handed. For example, the cholesteric liquid crystal display panel may include both left-handed tilted helical cholesteric liquid crystals and right-handed tilted helical cholesteric liquid crystals. The third substrate 5 may include a third electrode 51 and a fourth electrode 52 located on the upper and lower surfaces of the third substrate 5. For example, the third electrode 51 and the fourth electrode 52 may be ITO transparent conductive electrodes, that is, the third substrate 5 may be a substrate that is conductive on both sides. By regulating the voltage E1 between the first electrode 11 and the third electrode 51, the state of the cholesteric liquid crystal in the first sub-cholesteric liquid crystal layer 301 located between the first substrate 1 and the third substrate 5 can be regulated. By regulating the voltage E2 between the second electrode 21 and the fourth electrode 52, the state of the cholesteric liquid crystal in the second sub-cholesteric liquid crystal layer 302 located between the third substrate 5 and the second substrate 2 can be regulated, thereby achieving electric field control of different liquid crystal layers in the stacked liquid crystal display panel.

[0151] For example, by designing the range of illumination, the first sub-cholesteric liquid crystal layer 301 located between the first substrate 1 and the third substrate 5 can be transformed from the right-handed cholesteric phase to the left-handed cholesteric phase when illuminated, and the portion of the first sub-cholesteric liquid crystal layer 301 located between the second substrate 2 and the third substrate 5 that is not illuminated still maintains the right-handed cholesteric phase, thereby forming both left-handed and right-handed cholesteric phases in the tilted spiral cholesteric liquid crystal, and thus being able to simultaneously reflect left-handed and right-handed reflected light, thereby significantly improving the reflection contrast of the tilted spiral cholesteric liquid crystal.

[0152] FIG. 10 is a flowchart of manufacturing a cholesteric liquid crystal display panel according to some embodiments of the present disclosure.

[0153] 10 , at least some embodiments of the present disclosure further provide a method for manufacturing a cholesteric liquid crystal display panel, wherein the method includes the following steps S1-S2:

[0154] In step S1, a first substrate and a second substrate are provided;

[0155] In step S2, a cholesteric liquid crystal layer is formed between the first substrate and the second substrate.

[0156] Wherein, the cholesteric liquid crystal layer includes a cholesteric liquid crystal composition, the cholesteric liquid crystal composition includes the chiral photosensitive molecular switch as described above, or the cholesteric liquid crystal composition is the composition as described above.

[0157] FIG. 11 is a flow chart of forming a cholesteric liquid crystal layer between the first substrate and the second substrate in step S2 in FIG. 10 .

[0158] Exemplarily, forming a cholesteric liquid crystal layer between the first substrate and the second substrate in step S2 specifically includes the following steps S21-S22:

[0159] In step S21, the cholesteric liquid crystal composition is injected into the accommodation space formed between the first substrate and the second substrate;

[0160] In step S22, the cholesteric liquid crystal composition is irradiated with light of a predetermined wavelength to form a first cholesteric liquid crystal unit and a second cholesteric liquid crystal unit in the cholesteric liquid crystal layer.

[0161] The liquid crystal in the first cholesteric liquid crystal unit has a tilted helical structure with a first handedness, and the liquid crystal in the second cholesteric liquid crystal unit has a tilted helical structure with a second handedness, and the first handedness and the second handedness are opposite.

[0162] Since two cholesteric liquid crystals with different rotation directions are formed simultaneously in the cholesteric liquid crystal, such as left-handed tilted helical cholesteric liquid crystal and right-handed tilted helical cholesteric liquid crystal, both left-handed and right-handed reflected light can be reflected simultaneously, thereby greatly improving the reflection contrast of the tilted helical cholesteric liquid crystal.

[0163] FIG12 is a schematic diagram of illumination during preparation of step S22 according to some embodiments of the present disclosure.

[0164] For example, in some embodiments of the present disclosure, referring to FIG. 12 , forming a cholesteric liquid crystal layer 3 between the first substrate 1 and the second substrate 2 includes: injecting the cholesteric liquid crystal composition into the receiving space 4 formed between the first substrate 1 and the second substrate 2; irradiating the cholesteric liquid crystal composition with a mask 10 and light 20 of a predetermined wavelength, so that the handedness of the liquid crystals in the cholesteric liquid crystal layer that are not exposed to the light of the predetermined wavelength remains unchanged, thereby forming a first cholesteric liquid crystal cell 31; and flipping the handedness of the liquid crystals in the cholesteric liquid crystal layer that are exposed to the light of the predetermined wavelength, thereby forming a second cholesteric liquid crystal cell 32. For example, the first cholesteric liquid crystal cell 31 may include a tilted helical cholesteric liquid crystal having a first handedness, and the second cholesteric liquid crystal cell 32 may include a tilted helical cholesteric liquid crystal having a second handedness.

[0165] The design of the illumination range can make the cholesteric liquid crystal composition selectively covered by illumination. For example, the mask can be designed so that the cholesteric liquid crystal composition in a part of the display panel is covered by illumination, while the cholesteric liquid crystal composition in another part of the display panel is not covered by illumination due to the obstruction of the light-shielding portion of the mask. As a result, the cholesteric liquid crystal layer can simultaneously include a first cholesteric liquid crystal unit 31 having a first handedness tilted spiral structure and a second cholesteric liquid crystal unit 32 having a second handedness tilted spiral structure. For example, the cholesteric liquid crystal display panel can simultaneously include left-handed cholesteric liquid crystal and right-handed cholesteric liquid crystal.

[0166] For example, by applying an electric field to a cholesteric liquid crystal display panel and irradiating it with 450nm blue light through a photomask, the portion of the cholesteric liquid crystal exposed to the blue light undergoes a tilted helical structure flipping from right-handed to left-handed due to photosensitivity, while the unexposed portion retains its right-handed tilted helical structure. Furthermore, through chiral cancellation mechanisms and actual system HTP value testing, it is possible to precisely achieve a system in which both left-handed and right-handed helical twisting forces exhibit equal magnitude and opposite handedness. When the electric field is applied again, the system exhibits both left-handed and right-handed handednesses and reflects the same color, significantly improving the reflective contrast of the tilted helical liquid crystal device.

[0167] FIG13 is a schematic diagram of illumination during the preparation of step S22 according to other embodiments of the present disclosure.

[0168] For example, in some embodiments of the present disclosure, referring to FIG. 13 , forming a cholesteric liquid crystal layer between the first substrate 1 and the second substrate 2 includes:

[0169] injecting the cholesteric liquid crystal composition into the accommodation space 41 formed between the first substrate 1 and the third substrate 5 to form a first sub-cholesteric liquid crystal layer 301;

[0170] injecting the cholesteric liquid crystal composition into the accommodation space 42 formed between the third substrate 5 and the second substrate 2 to form a second sub-cholesteric liquid crystal layer 302;

[0171] The second sub-cholesteric liquid crystal layer 302 is irradiated with light of a predetermined wavelength. The liquid crystal of the second sub-cholesteric liquid crystal layer is exposed to the light of the predetermined wavelength and undergoes a rotational flip, thereby forming a second cholesteric liquid crystal unit 32. The liquid crystal of the first sub-cholesteric liquid crystal layer 301 is not exposed to the light of the predetermined wavelength and its rotational flip remains unchanged, thereby forming a first cholesteric liquid crystal unit 31.

[0172] By designing a display panel with a stacked cholesteric liquid crystal structure, one cholesteric liquid crystal layer is illuminated with light of a predetermined wavelength, while the other cholesteric liquid crystal layer is not illuminated. This allows the cholesteric liquid crystal layer to simultaneously include a first cholesteric liquid crystal unit having a tilted helical structure with a first handedness and a second cholesteric liquid crystal unit having a tilted helical structure with a second handedness, where the first handedness and the second handedness are opposite. For example, the first handedness can be left-handed, and the corresponding second handedness can be right-handed; alternatively, the first handedness can be right-handed, and the corresponding second handedness is left-handed. In other words, a cholesteric liquid crystal display panel can include both left-handed and right-handed cholesteric liquid crystals.

[0173] For example, in some embodiments of the present disclosure, the stacked conductive liquid crystal box is made of two conductive ITO-coated glass substrates that have been subjected to reverse planar processing and a double-sided conductive ITO-coated glass substrate that has been subjected to reverse planar processing. Specifically, the two conductive ITO-coated glass substrates that have been subjected to reverse planar processing are used to prepare the intermediate electrode, with the purpose of making the upper and lower layer systems share the same intermediate electrode. The system is first poured into the stacked liquid crystal box, and in one layer of the liquid crystal box, an electric field is applied and 450nm light is irradiated to a steady state. The liquid crystal box in this layer is induced to have a tilted spiral structure with a rotation direction opposite to that of the other layer of the liquid crystal system due to the presence of a chiral photosensitive molecular switch, so that the stacked liquid crystal box can simultaneously reflect left-handed and right-handed reflected light, and ultimately achieve a significant improvement in the reflection contrast of the tilted spiral liquid crystal device.

[0174] Through mask design or stacked liquid crystal structure design, steady-state regulation of different regions in the tilted spiral cholesteric phase liquid crystal can be achieved, so that left-handed tilted spiral cholesteric phase liquid crystal and right-handed tilted spiral cholesteric phase liquid crystal exist simultaneously in the liquid crystal, so that the liquid crystal box can reflect left-handed and right-handed reflected light at the same time, and ultimately achieve a significant improvement in the reflection contrast of the tilted spiral liquid crystal device.

[0175] Although some embodiments of the overall technical concept of the present disclosure have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the overall technical concept, and the scope of the present disclosure is defined by the claims and their equivalents.

Claims

1. A chiral photosensitive molecular switch, wherein: The chemical structure of the chiral photosensitive molecular switch is shown in the following general formula I: Among them, M1 is selected from The groups R1 and R2 are the same or different and include a benzene ring, a biphenyl ring, an aromatic ring or an aromatic heterocycle; L1 and L2 include C1 to C 10 of alkyl.

2. The chiral photosensitive molecular switch according to claim 1, wherein: The chemical structure of at least one of the groups R1 and R2 is shown in one of the following formulae:

3. The chiral photosensitive molecular switch according to claim 1 or 2, wherein: The chemical structure of the chiral photosensitive molecular switch is shown in one of the following formulas:

4. A cholesteric liquid crystal composition, wherein: The composition comprises the chiral photosensitive molecular switch according to any one of claims 1 to 3.

5. The cholesteric liquid crystal composition according to claim 4, wherein: The composition also includes a bent molecule mixture, a rod-shaped single crystal mixture, and a non-photosensitive chiral dopant.

6. The cholesteric liquid crystal composition according to claim 5, wherein: Based on the weight of the cholesteric liquid crystal composition, the chiral photosensitive molecular switch accounts for 0.5% to 10%.

7. The cholesteric liquid crystal composition according to claim 5 or 6, wherein: Based on the weight of the cholesteric liquid crystal composition, the non-photosensitive chiral dopant accounts for 0.5% to 10%.

8. The cholesteric liquid crystal composition according to any one of claims 5 to 7, wherein: Based on the weight of the cholesteric liquid crystal composition, the bent molecule mixture accounts for 30% to 70%, or the rod-shaped single crystal mixture accounts for 30% to 70%.

9. The cholesteric liquid crystal composition according to any one of claims 5 to 7, wherein: Based on the weight of the cholesteric liquid crystal composition, the proportion of the bent molecular mixture is 30% to 70%, the proportion of the rod-shaped single crystal mixture is 30% to 70%, the proportion of the chiral photosensitivity molecular switch is 5% to 10%, the proportion of the non-photosensitive chiral dopant is 5% to 10%, and the sum of the proportion of the bent molecular mixture, the proportion of the rod-shaped single crystal mixture, the proportion of the chiral photosensitivity molecular switch and the proportion of the non-photosensitive chiral dopant is 100%.

10. A cholesteric liquid crystal display panel, wherein: The display panel comprises: A first substrate and a second substrate arranged opposite to each other; a cholesteric liquid crystal layer located between the first substrate and the second substrate, Wherein, the cholesteric liquid crystal layer comprises a cholesteric liquid crystal composition, and the cholesteric liquid crystal composition comprises the chiral photosensitive molecular switch according to any one of claims 1 to 3, or the cholesteric liquid crystal composition is the composition according to any one of claims 5 to 9.

11. The display panel according to claim 10, wherein: The cholesteric liquid crystal layer includes a first cholesteric liquid crystal unit and a second cholesteric liquid crystal unit, the liquid crystal in the first cholesteric liquid crystal unit has a tilted spiral structure with a first handedness, and the liquid crystal in the second cholesteric liquid crystal unit has a tilted spiral structure with a second handedness, and the first handedness is opposite to the second handedness.

12. The display panel according to claim 11, wherein: An absolute value of a helical twisting force of liquid crystal in the first cholesteric liquid crystal cell is substantially equal to an absolute value of a helical twisting force of liquid crystal in the second cholesteric liquid crystal cell.

13. The display panel according to any one of claims 10 to 12, wherein: The display panel further includes: a first electrode located on the first substrate and a second electrode located on the second substrate; The cholesteric liquid crystal layer is configured such that a wavelength corresponding to a reflection peak of the cholesteric liquid crystal layer changes as a voltage applied between the first electrode and the second electrode changes.

14. The display panel according to claim 13, wherein: The cholesteric liquid crystal layer is configured such that: in response to a first voltage applied between the first electrode and the second electrode, a reflection peak of the cholesteric liquid crystal layer corresponds to a first wavelength; In response to a second voltage applied between the first electrode and the second electrode, a reflection peak of the cholesteric liquid crystal layer corresponds to a second wavelength; In response to a third voltage applied between the first electrode and the second electrode, a reflection peak of the cholesteric liquid crystal layer corresponds to a third wavelength, The first voltage, the second voltage and the third voltage are different from each other, and the first wavelength, the second wavelength and the third wavelength correspond to visible light of different colors respectively.

15. The display panel according to claim 14, wherein: The cholesteric liquid crystal layer is configured such that as a voltage applied between the first electrode and the second electrode decreases, a wavelength corresponding to a reflection peak of the cholesteric liquid crystal layer increases.

16. The display panel according to claim 15, wherein: The first voltage is higher than the second voltage, and the second voltage is higher than the third voltage; The first wavelength is smaller than the second wavelength, and the second wavelength is smaller than the third wavelength.

17. The display panel according to claim 11, wherein: The first substrate and the second substrate are paired to form a containing space, the cholesteric liquid crystal layer is located in the containing space, and the orthographic projections of the first cholesteric liquid crystal unit and the second cholesteric liquid crystal unit on the first substrate are alternately distributed.

18. The display panel according to claim 11, wherein: The display panel further includes a third substrate located between the first substrate and the second substrate. The cholesteric liquid crystal layer includes: a first sub-cholesteric liquid crystal layer located between the first substrate and the third substrate; and a second sub-cholesteric liquid crystal layer located between the third substrate and the second substrate. The first sub-cholesteric liquid crystal layer includes the first cholesteric liquid crystal unit, and the second sub-cholesteric liquid crystal layer includes the second cholesteric liquid crystal unit.

19. A method for preparing a cholesteric liquid crystal display panel, wherein: The method comprises: providing a first substrate and a second substrate; forming a cholesteric liquid crystal layer between the first substrate and the second substrate, Wherein, the cholesteric liquid crystal layer comprises a cholesteric liquid crystal composition, and the cholesteric liquid crystal composition comprises the chiral photosensitive molecular switch according to any one of claims 1 to 3, or the cholesteric liquid crystal composition is the composition according to any one of claims 5 to 9.

20. The preparation method according to claim 19, wherein The forming of a cholesteric liquid crystal layer between the first substrate and the second substrate comprises: injecting the cholesteric liquid crystal composition into a receiving space formed between the first substrate and the second substrate; irradiating the cholesteric liquid crystal composition with light of a predetermined wavelength to form a first cholesteric liquid crystal unit and a second cholesteric liquid crystal unit in the cholesteric liquid crystal layer, The liquid crystal in the first cholesteric liquid crystal unit has a tilted spiral structure with a first handedness, and the liquid crystal in the second cholesteric liquid crystal unit has a tilted spiral structure with a second handedness, and the first handedness is opposite to the second handedness.

21. The preparation method according to claim 20, wherein: The forming of a cholesteric liquid crystal layer between the first substrate and the second substrate comprises: injecting the cholesteric liquid crystal composition into a receiving space formed between the first substrate and the second substrate; The cholesteric liquid crystal composition is irradiated with a mask and light of a predetermined wavelength, so that the rotational orientation of the liquid crystal in the cholesteric liquid crystal layer that is not exposed to the light of the predetermined wavelength remains unchanged to form a first cholesteric liquid crystal unit; and the rotational orientation of the liquid crystal in the cholesteric liquid crystal layer that is exposed to the light of the predetermined wavelength is reversed to form a second cholesteric liquid crystal unit.

22. The preparation method according to claim 20, wherein: The forming of a cholesteric liquid crystal layer between the first substrate and the second substrate comprises: injecting the cholesteric liquid crystal composition into a receiving space formed between the first substrate and the third substrate to form a first sub-cholesteric liquid crystal layer; injecting the cholesteric liquid crystal composition into a receiving space formed between the third substrate and the second substrate to form a second sub-cholesteric liquid crystal layer; The second sub-cholesteric liquid crystal layer is irradiated with light of a predetermined wavelength, and the liquid crystal of the second sub-cholesteric liquid crystal layer is exposed to the light of the predetermined wavelength and its rotational orientation is flipped to form a second cholesteric liquid crystal unit; the liquid crystal of the first sub-cholesteric liquid crystal layer is not exposed to the light of the predetermined wavelength and its rotational orientation remains unchanged to form a first cholesteric liquid crystal unit.

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