Reflective liquid crystal display panel and its manufacturing method, reflective liquid crystal display device

Abstract

This application relates to the field of liquid crystal display technology, specifically to a reflective liquid crystal display panel and its preparation method, and a reflective liquid crystal display device. The reflective liquid crystal display panel includes a first substrate, a liquid crystal layer, and a second substrate stacked sequentially. The raw material components of the cholesteric liquid crystal composition include nematic liquid crystal, a hydrophobic first chiral compound, and a hydrophilic second chiral compound, with opposite optical rotations between the first and second chiral compounds. A hydrophilic interface is formed on the side of one of the first and second substrates facing the liquid crystal layer. This overcomes the limitation that the theoretical reflectivity of a single optically active cholesteric liquid crystal does not exceed 50%, improving overall reflectivity and display brightness. Because the components with different optical rotations are vertically layered within the same continuous liquid crystal phase, rather than forming an independent double-layer structure through external bonding, there are no obvious independent mechanical interfaces between the layers, reducing light scattering loss and improving optical coupling efficiency.

Description

Technical Field

[0001] This application relates to the field of liquid crystal display technology, and more specifically, to a reflective liquid crystal display panel and its preparation method, and a reflective liquid crystal display device. Background Technology

[0002] While traditional display panels (such as LCD panels) are thin, durable, and energy-efficient, they require a backlight, which increases the overall thickness of the module and raises production and application costs. Against this backdrop, electronic paper reflective displays have emerged as a new display solution that meets the needs of the general public. These displays can display images using natural or ambient light, unlike LCDs which rely on a backlight. Therefore, even in bright outdoor sunlight, users can clearly read information on the electronic paper without limited viewing angles. Currently, there are various mainstream electronic paper display technologies, including E-Ink microcapsule technology, SiPix microcup technology, Bridgestone electronic liquid powder technology, Cholesteric Liquid Crystal Display (CLCD), and electrowetting technology.

[0003] Among these technologies, the core advantage of cholesteric liquid crystal display technology lies in its bistable characteristic, specifically manifested in two stable states: planar and focal conical. This is because the cholesteric liquid crystal has a specific pitch; when its pitch is close to the wavelength of the incident light, it can selectively reflect specific wavelengths of light. Applying a voltage can regulate the alignment of the cholesteric liquid crystal molecules, allowing it to switch between these two stable states. When the cholesteric liquid crystal is in a planar alignment, it selectively reflects light of a specific wavelength; conversely, when in a focal conical alignment, light can pass through directly. Based on this characteristic, by applying a voltage to the cholesteric liquid crystal, it can be controlled to exhibit either a state of "allowing light to pass through" or "reflecting light of a specific wavelength." This process allows the displayed content to remain active without continuous power supply, significantly reducing power consumption. This characteristic makes it widely used in e-books, e-paper, electronic whiteboards, outdoor billboards, and other products requiring low power consumption.

[0004] However, existing monochrome cholesteric liquid crystal display technology faces a core bottleneck that is difficult to overcome. Traditional single-layer structures are limited by the single-rotation light reflection principle of the liquid crystal layer, and their theoretical reflectivity cannot exceed 50%, resulting in insufficient display brightness and poor visibility under strong outdoor light. Among related technologies, there are dual-layer structure solutions attempting to overcome the reflectivity limit. These typically employ a physical stacking process to prepare left-handed and right-handed liquid crystal layers separately, followed by physical bonding or secondary coating. This step-by-step manufacturing process has significant drawbacks: firstly, the two independent coating or printing processes increase production costs and time, reducing yield; secondly, the dual-layer liquid crystal structure lacks sufficient mechanical support, making it prone to interlayer slippage or uneven thickness under external pressure or bending, leading to color spots and performance degradation; and thirdly, the unavoidable physical spacers or air between the materials of the multi-layer liquid crystal layers limit the improvement in reflectivity. Summary of the Invention

[0005] The technical problem this application aims to solve is that single-layer cholesteric liquid crystal layers have insufficient reflectivity, while cholesteric liquid crystal layers with a double-layer physical stacked structure are not only cumbersome in process, expensive, and have poor mechanical stability, but also have limited reflectivity improvement due to the presence of physical spacers or air between layers. To solve the above technical problems, embodiments of this application provide a reflective liquid crystal display panel and its manufacturing method, as well as a reflective liquid crystal display device.

[0006] To achieve the above objectives, according to the first aspect of this technical solution, this technical solution provides a reflective liquid crystal display panel.

[0007] According to an embodiment of this application, a reflective liquid crystal display panel includes a first substrate, a liquid crystal layer, and a second substrate stacked sequentially, wherein the liquid crystal layer includes a liquid crystal film made of a cholesteric liquid crystal composition;

[0008] The raw material components of the cholesterol-type liquid crystal composition include nematic liquid crystal, a hydrophobic first chiral compound, and a hydrophilic second chiral compound, wherein the first chiral compound and the second chiral compound have opposite optical rotations.

[0009] A hydrophilic interface is formed on the side of the first substrate and the second substrate facing the liquid crystal layer.

[0010] Furthermore, the first chiral compound is selected from R811, S811, CB15 (S), CB15 (R), R1011 and S1011.

[0011] Further, the second chiral compound is selected from R811-OH, S811-OH, R1011-OH, S1011-OH, dihydroxyl-modified chiral compounds, polyoxyethylene ether-modified chiral compounds, and carboxyl-modified chiral compounds.

[0012] Furthermore, the raw material components of the cholesterol-type liquid crystal composition also include a photoinitiator and a polymeric monomer, wherein the photoinitiator is configured to initiate a polymerization reaction of the polymeric monomer upon exposure to light.

[0013] Furthermore, the photoinitiator is selected from TPO, DMAP, photoinitiator 907 and photoinitiator 184; the polymerizing monomer is selected from 2-EHA, TMPTA, PEGMEA and HEMA.

[0014] Furthermore, the hydrophilic interface is formed by bombarding the surface of the substrate with oxygen plasma, by treating the surface of the substrate with ultraviolet ozone, or by coating with a hydrophilic coating.

[0015] Furthermore, a hydrophobic interface is formed on the side of the first substrate and the second substrate facing the liquid crystal layer.

[0016] Furthermore, the hydrophobic interface is formed by bombarding the surface of the substrate with CF4 plasma, bombarding the surface of the substrate with C4F8 plasma, or by coating with a hydrophobic coating.

[0017] Furthermore, the first substrate is located on the display side of the reflective liquid crystal display panel relative to the second substrate, the hydrophobic interface is located on the side of the first substrate facing the liquid crystal layer, and the hydrophilic interface is located on the side of the second substrate facing the liquid crystal layer.

[0018] To achieve the above objectives, according to a second aspect of this technical solution, a method for fabricating a reflective liquid crystal display panel is provided for fabricating the reflective liquid crystal display panel provided in the first aspect of this application. The method includes:

[0019] A first substrate and a second substrate are provided respectively, and the inner surface of one of the substrates is hydrophilized to form a hydrophilic interface and a glue frame.

[0020] The raw material components of the cholesterol-type liquid crystal composition are mixed to obtain a uniform and stable liquid crystal composition mixing system;

[0021] A liquid crystal composition mixture is coated onto the surface of a first substrate or a second substrate to form a liquid crystal thin film structure.

[0022] The first substrate and the second substrate are fastened together so that the first substrate and the second substrate are connected by a glue frame.

[0023] To achieve the above objectives, according to a third aspect of this technical solution, this technical solution provides a reflective liquid crystal display device, which includes the reflective liquid crystal display panel provided in the first aspect of this technical solution.

[0024] The embodiments of this application have the following beneficial effects:

[0025] In this way, a structure with similar functionality to bilayer left- and right-handed cholesterol liquid crystals can be achieved using a single-layer fabrication process. On one hand, because the two chiral components with opposite optical rotations are distributed in layers along the thickness direction, the liquid crystal layer can selectively reflect incident light in different optical rotation directions at different layers. This helps to overcome the limitation that the theoretical reflectivity of traditional single-axis cholesterol liquid crystals does not exceed 50%, thus improving overall reflectivity and display brightness. On the other hand, since this layered structure is spontaneously generated within a continuous liquid crystal layer formed in a single coating, it eliminates the need for two separate coatings, printing, or physical bonding methods used in existing technologies. Therefore, it can significantly reduce manufacturing steps, lower production costs and time, and improve process yield.

[0026] Furthermore, since the two chiral components with different optical rotations are vertically layered within the same continuous liquid crystal phase, rather than forming an independent double-layer structure through external bonding, there are no obvious independent mechanical interfaces between the layers, and it is less likely to form air layers, bubble interfaces, or impurity interfaces common in traditional double-layer structures. This reduces light scattering loss, improves optical coupling efficiency, and enhances the mechanical stability of the entire liquid crystal layer structure, making it less prone to interlayer slippage, uneven thickness, or color spots under external pressure, bending, or long-term use. Through the above design, the embodiments of this application can achieve a comprehensive improvement in higher reflectivity, simplified process, and higher structural stability while maintaining the advantages of cholesteric liquid crystal bistable and low-power display. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings:

[0028] Figure 1 This is a schematic diagram illustrating the display principle of single-layer cholesterol-type liquid crystal display technology in related technologies;

[0029] Figure 2 This is a schematic diagram illustrating the display principle of dual-layer cholesterol-type liquid crystal display technology in related technologies;

[0030] Figure 3 This is a cross-sectional view of the reflective liquid crystal display panel provided in the embodiments of this application in a state where a cholesteric liquid crystal composition forms a layered structure.

[0031] Figure 4This is a schematic diagram illustrating the principle of forming a layered structure using a cholesterol-type liquid crystal composition provided in the embodiments of this application.

[0032] Figure 5 This is a schematic diagram illustrating the display principle of the layered structure formed by the cholesterol-type liquid crystal composition provided in the embodiments of this application;

[0033] Figure 6 This is a cross-sectional view of the reflective liquid crystal display panel provided in the embodiments of this application in a state where the cholesterol-type liquid crystal composition has not formed a layered structure;

[0034] Figure 7 This is a flowchart illustrating the fabrication process of the reflective liquid crystal display panel provided in an embodiment of this application.

[0035] In the picture:

[0036] 100, First substrate; 110, Carrier substrate; 120, ITO electrode layer;

[0037] 200. Second substrate;

[0038] 300. Liquid crystal layer; 310. Liquid crystal film; 320. Frame;

[0039] 400, light-absorbing layer;

[0040] 1. Levorotatory cholesterol liquid crystal; 2. Devorotatory cholesterol liquid crystal; 3. Incident light; 4. Reflected light; 5. Transmitted light; 6. Bubble / impurity physical interface; 7. Light scattering loss; 8. Hydrophilic interface; 9. Natural light; 10. Reflected devorotatory light; 11. Transmitted levorotatory light; 12. Reflected levorotatory light. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0042] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a system, product or device that includes a series of units is not necessarily limited to those units that are explicitly listed, but may include units that are not explicitly listed or that are inherent to such products or devices.

[0043] In this application, the terms "upper," "lower," "inner," "middle," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0044] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0045] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0046] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0047] Figure 1 This diagram illustrates the display principle of single-layer cholesteric liquid crystal display technology, specifically demonstrating the principle of planar cholesteric liquid crystal reflecting specific wavelengths. Cholesteric liquid crystal material is a nematic liquid crystal whose molecules' long axes are rotated in a specific arrangement. The necessary distance for the long axis of the liquid crystal molecules to rotate 360° is called the helical pitch. This helical structure causes linearly polarized visible light to pass through it, causing the polarization plane to rotate in the plane perpendicular to the helical axis. Therefore, this type of liquid crystal exhibits optical rotation, which can be either right-handed or left-handed depending on its structure. This property allows for the reflection or transmission of light. Figure 1 As shown, a left-handed cholesteric liquid crystal 1 is sandwiched between a first substrate 100 and a second substrate 200, with a pitch of P. If the wavelength of a light ray is λ, the average refractive index of this left-handed cholesteric liquid crystal 1 is n, and the angle between the incident light 3 and the helical axis is θ, when λ = P × n × cosθ, a portion of the light ray will be reflected as left-handed circularly polarized light to form reflected light 4, and a portion of the light ray will penetrate this cholesteric liquid crystal as right-handed circularly polarized light to form transmitted light 5. Figure 1In the cholesteric liquid crystal display structure shown, since cholesteric liquid crystals can only reflect light with a single rotation (such as left-handed or right-handed light), its reflectivity has a physical limit. Even if the light with a single rotation is totally reflected under ideal conditions, the limit value of the reflectivity of the incident light can only be 50%.

[0048] Figure 2 This illustrates the display principle of a dual-layer cholesteric liquid crystal display technology. Two layers of cholesteric liquid crystal, levorotatory cholesteric liquid crystal 1 and dextrorotatory cholesteric liquid crystal 2, are fabricated using a physical stacking process. These layers are then physically bonded or coated a second time to form a display. Figure 2 The diagram shows a double-layer structure sandwiched between a first substrate 100 and a second substrate 200. For example... Figure 2 The upper and middle layers are composed of right-handed cholesteric liquid crystal 2, and the lower layer is composed of left-handed cholesteric liquid crystal 1. When natural light 3 enters the upper layer as incident light 3, some of the light is reflected as right-handed circularly polarized light, while some of the light penetrates the upper cholesteric liquid crystal as left-handed circularly polarized light and enters the lower layer. The left-handed circularly polarized light entering the lower layer is further reflected by the lower left-handed cholesteric liquid crystal. This superposition of reflections from the upper and lower layers creates reflected light 4, increasing the overall reflectivity. However, Figure 2 The dual-layer structure shown employs two independent coating or printing processes, increasing production costs and time, and reducing product yield. Furthermore, the dual-layer liquid crystal structure lacks sufficient mechanical support, making it prone to interlayer slippage or uneven thickness under external pressure or bending, leading to color spots and performance degradation. In addition, physical spacers or air pockets inevitably exist between the materials of the multi-layer liquid crystal layers, for example… Figure 2 The bubble / impurity physical interface 6 in the middle will cause a lot of light scattering loss 7, thus limiting the improvement of reflectivity.

[0049] like Figure 3 and Figure 6 As shown in the illustration, this application provides a reflective liquid crystal display panel, comprising a first substrate 100, a liquid crystal layer 300, and a second substrate 200 stacked sequentially, wherein the liquid crystal layer 300 is located between the first substrate 100 and the second substrate 200. The liquid crystal layer 300 includes a liquid crystal film 310 made of a cholesteric liquid crystal composition. The raw material components of the cholesteric liquid crystal composition include a nematic liquid crystal, a hydrophobic first chiral compound, and a hydrophilic second chiral compound, wherein the first chiral compound and the second chiral compound have opposite optical rotations. A hydrophilic interface is formed on the side of one of the first substrate 100 and the second substrate 200 facing the liquid crystal layer 300.

[0050] Specifically, the first substrate 100 and the second substrate 200 are disposed opposite to each other, forming a display cavity between them for accommodating the liquid crystal film 310. The liquid crystal film 310 is filled in the display cavity and is formed by coating the cholesteric liquid crystal composition. Since the cholesteric liquid crystal composition contains both a first chiral compound and a second chiral compound with opposite optical rotation and different hydrophilicity and hydrophobicity, a vertically layered structure in the thickness direction can be formed during the film formation process under the action of hydrophilicity and hydrophobicity and hydrogen bonding effects, so that regions with different optical rotation characteristics are formed inside the liquid crystal layer 300. Through this structure, the liquid crystal layer 300 can selectively reflect incident light in different optical rotation directions, thereby improving the overall reflectivity.

[0051] The working principle of the reflective liquid crystal display panel is as follows: A voltage of a specific amplitude is applied to the electrodes through the TFT driving circuit of the second substrate 200 to control the switching of the cholesteric liquid crystal between the planar state and the focal conical state. When it is in the planar state, the cholesteric liquid crystal of the upper layer with a specific rotation direction and the cholesteric liquid crystal of the lower layer with the opposite rotation direction superimpose and reflect the target wavelength light to achieve high brightness monochrome display. When it is in the focal conical state, the light passes through the cholesteric liquid crystal and the display is transparent. After the voltage is removed, the cholesteric liquid crystal maintains the current steady state and does not require continuous power supply to achieve low power consumption display.

[0052] Unlike traditional techniques that employ two independent coating processes or physical bonding to form a bilayer cholesterol-type liquid crystal structure, this embodiment introduces a phase separation driving mechanism within a single liquid crystal mixture system. This enables chiral components with different optical rotations to spontaneously separate within the liquid crystal layer 300 formed in a single coating. Specifically, this embodiment innovatively utilizes the hydrophilic-hydrophobic interface effect as the driving force for separation. Through interfacial adsorption, it promotes the directional migration and separation of different chiral components in the liquid crystal system, thereby automatically forming upper and lower layered liquid crystal layers with an ordered structure within a single liquid crystal coating.

[0053] like Figure 4 As shown, in this embodiment, the cholesterol-type liquid crystal composition simultaneously contains two chiral compounds with opposite optical rotation directions. In the initial mixed state, since the two chiral components are uniformly dispersed in the nematic liquid crystal system, the overall system typically exhibits a single optical rotation and reflection characteristic dominated by one type of chiral component, i.e., following the chiral induction law of majority rule, thus exhibiting selective reflection in a single optical rotation direction. However, after the liquid crystal composition is coated onto the substrate surface and a liquid crystal layer 300 is formed, due to the presence of a hydrophilic interface on one substrate surface, for example… Figure 4A hydrophilic interface 8 is formed on the surface of the second substrate 200. This hydrophilic interface 8 exhibits a significant interfacial adsorption effect on hydrophilic components in the liquid crystal system. Specifically, driven by the hydrophilic-hydrophobic interface effect, hydrophilic second chiral compounds ( Figure 4 Taking a levorotatory chiral compound as an example, the liquid crystal component it induces migrates to the hydrophilic interface 8 under the drive of interfacial chemical potential energy and accumulates at this interface, while simultaneously wetting the surface of the second substrate 200, forming a levorotatory cholesterol-type liquid crystal 1. Meanwhile, the first chiral compound (which has hydrophobic properties) Figure 4 Taking a dextrorotatory chiral compound as an example, the liquid crystal component induced by it will be repelled by the hydrophilic interface 8, and thus spontaneously migrate away from the hydrophilic interface 8 and accumulate near the substrate on the other side, forming a dextrorotatory cholesterol-type liquid crystal 2.

[0054] It should also be noted that a hydrophilic interface is formed on the side of one of the first substrate 100 and the second substrate 200 facing the liquid crystal layer 300. This hydrophilic interface not only drives the directional migration of different components within the liquid crystal system through the hydrophilic-hydrophobic interface effect, but also further promotes the formation of layering through interfacial intermolecular interactions. Specifically, the hydrophilic secondary chiral compounds contained in the liquid crystal composition typically have polar functional groups, such as hydroxyl, carboxyl, ether bonds, or other groups capable of forming hydrogen bonds. When the liquid crystal composition is coated on the substrate surface and forms the liquid crystal layer 300, the hydrophilic interface on the substrate surface preferentially adsorbs these polar hydrophilic secondary chiral compounds and forms hydrogen bonds with them at the interface. This hydrogen bonding can generate strong intermolecular forces near the interface, thereby significantly reducing the free energy of the hydrophilic components at the interface, making the hydrophilic secondary chiral compounds and the liquid crystal components they induce more stably enriched in the interface region.

[0055] Driven by both interfacial hydrogen bonding and hydrophilic-hydrophobic interface effects, the hydrophilic secondary chiral compound and its induced liquid crystal molecules rapidly migrate to the hydrophilic interface and form a stable enriched layer there. Conversely, the hydrophobic primary chiral compound and its induced liquid crystal components are repelled and migrate away from the interface, resulting in a distinct upper and lower layered structure along the 300mm thickness of the liquid crystal layer. Thus, the upper and lower layers are dominated by chiral components with different optical rotations, thereby constructing a cholesteric liquid crystal stacked structure with opposite optical rotations.

[0056] In contrast, if a hydrophobic interface is formed only on the surface of a substrate, it is difficult to provide a clear and stable interfacial adsorption site for a particular type of chiral component in the liquid crystal system because the hydrophobic interface usually relies mainly on van der Waals forces or weak interfacial repulsion to influence molecular distribution, lacking strong directional intermolecular interactions such as hydrogen bonds. In this case, the delamination driving force within the system, relying solely on hydrophobic repulsion, is weak and easily affected by thermal or flow disturbances, making it difficult to form a stable and clear vertical delamination structure, ultimately resulting in an unsatisfactory delamination effect.

[0057] like Figure 5 As shown, through this spontaneous layered structure, the upper and lower cholesteric liquid crystal layers selectively reflect circularly polarized light with different optical rotation directions. Figure 5 Taking a structure with a top layer of dextrorotatory cholesteric liquid crystal 2 and a bottom layer of levorotatory cholesteric liquid crystal 1 as an example, when natural light 9 is incident on this structure, a portion of the light is first reflected at the top dextrorotatory cholesteric liquid crystal 2, forming reflected dextrorotatory light 10. The other component of light, which is not reflected, passes through the top dextrorotatory cholesteric liquid crystal 2, forming transmitted levorotatory light 11, which continues to propagate to the bottom levorotatory cholesteric liquid crystal 1 and is reflected, forming reflected levorotatory light 12. Through the superposition of reflections from the two liquid crystal layers, both levorotatory and dextrorotatory light can be reflected simultaneously, thereby achieving a super-reflective effect and breaking through the physical limitation of 50% for the overall reflectivity of traditional single-layer cholesteric liquid crystal structures.

[0058] Through the above structural design, this embodiment can achieve spontaneous layering of the optical rotation structure in the liquid crystal layer formed by a single coating without using double-layer coating or physical bonding processes. This simplifies the manufacturing process, reduces production costs, and avoids problems such as interlayer slippage, uneven thickness, and physical interface scattering that are easy to occur in traditional double-layer structures. It also significantly improves reflectivity and display brightness while improving structural stability.

[0059] In some embodiments, the nematic liquid crystal serves as the host material of a cholesteric liquid crystal system, providing the nematic matrix environment required for the formation of the cholesteric liquid crystal structure. The nematic liquid crystal can be selected from common nematic liquid crystal materials with good liquid crystal phase stability and electro-optic response characteristics, including but not limited to alkylcyanobiphenyl liquid crystals, alkoxycyanobiphenyl liquid crystals, phenylcyclohexane cyano liquid crystals, dicyclohexane cyanobenzene liquid crystals, alkylcyanoterphenyl liquid crystals, or other commercially available nematic mixed crystal systems.

[0060] The alkyl cyanobiphenyl liquid crystal can be selected from at least one of 5CB (4-pentyl-4'-cyanobiphenyl), 6CB (4-hexyl-4'-cyanobiphenyl), 7CB (4-heptyl-4'-cyanobiphenyl), or 8CB (4-octyl-4'-cyanobiphenyl). These liquid crystal materials exhibit high anisotropy and good nematic phase stability, and can form stable helical structures in cholesteric liquid crystal systems.

[0061] The alkoxycyanobiphenyl liquid crystal can be selected from at least one of 5OCB (4-pentoxy-4'-cyanobiphenyl) or 6OCB (4-hexyloxy-4'-cyanobiphenyl). Due to the introduction of alkoxy substituents, this type of liquid crystal material usually has lower viscosity and better low-temperature performance, which is beneficial for the liquid crystal system to maintain the nematic phase over a wider temperature range.

[0062] The phenylcyclohexane cyanide liquid crystal can be selected from at least one of PCH-3, PCH-5 or PCH-7. This type of liquid crystal material usually has low viscosity and fast electro-optic response speed, which can improve the response characteristics of the liquid crystal system.

[0063] The dicyclohexane cyanobenzene liquid crystal can be selected from at least one of CCH-3, CCH-4 or CCH-5. This type of liquid crystal material has a high clearing point and good thermal stability, which is beneficial to improving the temperature adaptability of the liquid crystal system.

[0064] The alkyl cyanotriphenyl liquid crystal can be selected from at least one of 5CT, 6CT or 7CT. This type of liquid crystal material has a large birefringence and strong optical anisotropy, which is beneficial to improving the optical reflection performance of cholesterol liquid crystal.

[0065] In some embodiments, the nematic liquid crystal can also be a commercially available mixed crystal system, such as E7, E44, E48, BL006, or BL038. Commercially available mixed crystals are typically composed of multiple nematic liquid crystal materials mixed in a specific ratio. They possess good phase stability, a wide nematic phase temperature range, and stable electro-optic properties, providing a stable matrix environment for cholesteric liquid crystal systems.

[0066] By selecting one or more of the above-mentioned nematic liquid crystals as the host liquid crystal material, and combining them with the first chiral compound and the second chiral compound to form a cholesterol-type liquid crystal composition, a cholesterol-type liquid crystal system with a stable helical structure can be formed, thereby achieving selective reflection of light of a specific wavelength and providing a stable liquid crystal phase basis for subsequent spontaneous layering structures.

[0067] In some embodiments, the first chiral compound is selected from at least one of R811 (CAS No.: 133676-09-2), S811 (CAS No.: 87321-20-8), R1011 (CAS No.: 103974-24-9), S1011 (CAS No.: 165660-09-3), CB15(S) (CAS No.: 59137-36-9), and CB15(R) (CAS No.: 114884-45-6). These compounds are all commonly used chiral dopants for cholesteric liquid crystals in the art, capable of inducing stable helical structures in nematic liquid crystal systems and imparting specific optical rotation to the liquid crystal system. By adjusting the proportion of chiral compounds added, the pitch of the cholesteric liquid crystal can be precisely controlled, thereby achieving selective reflection of light of the target wavelength. In this embodiment, the first chiral compound is configured as a hydrophobic chiral component, whose molecular structure typically contains long alkyl chains or aromatic structures, giving it low polarity and strong hydrophobic properties. When the cholesteric liquid crystal composition is coated between substrates to form a liquid crystal layer, the hydrophobic first chiral compound, driven by interfacial energy, tends to migrate away from the hydrophilic interface and to the other side due to the presence of a hydrophilic interface on at least one substrate surface, thus gradually accumulating in the region of the liquid crystal layer away from the hydrophilic interface. Simultaneously, the first chiral compound exhibits a distinct optical rotation induction ability. For example, R1011, R811, and CB15(R) typically exhibit dextrorotatory induction characteristics, while S1011, S811, and CB15(S) exhibit levorotatory induction characteristics. After spontaneous layering of the liquid crystal system, the first chiral compound forms an enriched region on the side away from the hydrophilic interface, dominating the helical arrangement of liquid crystal molecules in this region, thereby forming a cholesteric liquid crystal layer with a specific optical rotation direction.

[0068] The second chiral compound is selected from at least one of the following: R811-OH (Formula 1), S811-OH (Formula 2), R1011-OH (Formula 3), S1011-OH (Formula 4), other dihydroxyl-modified chiral compounds, modified chiral compounds containing polyoxyethylene ethers, and carboxyl-modified chiral compounds (e.g., converting -CH2OH in Formulas 1-4 to -COOH via oxidation). While maintaining chiral induction ability, these compounds exhibit significant hydrophilic properties by introducing polar functional groups into their molecular structure, thereby enabling strong interfacial interactions with the hydrophilic interface on the substrate surface. Specifically, R811-OH, S811-OH, R1011-OH, and S1011-OH are modified compounds obtained by introducing hydroxyl functional groups into the molecular structures of traditional chiral dopants R811, S811, R1011, and S1011. Hydroxyl groups possess strong polarity and can form hydrogen bonds with the hydrophilic interface of the substrate surface, thereby enhancing the adsorption capacity of the molecule at the interface. Similarly, dihydroxyl-modified chiral compounds, by introducing two or more hydroxyl groups into their molecular structure, can further improve their hydrophilicity and interfacial adsorption capacity, making them more easily enriched at hydrophilic interfaces. Polyoxyethylene ether-modified chiral compounds, by introducing polyoxyethylene segments into their chiral molecular structure, endow the molecules with certain hydrophilic and lipophilic amphiphilic properties. These polyoxyethylene segments can interact strongly with the hydrophilic interface, thus promoting the aggregation of such chiral components near the hydrophilic interface. Carboxyl-modified chiral compounds, by introducing carboxyl functional groups into their molecular structure, possess stronger polarity and hydrogen bonding ability, thereby further enhancing interfacial adsorption with hydrophilic interfaces.

[0069]

[0070] Formula 1

[0071]

[0072] Formula 2

[0073]

[0074] Formula 3

[0075]

[0076] Formula 4

[0077] By employing the above method, a hydrophilic second-chiral compound is selected, which preferentially migrates to and accumulates at the hydrophilic interface after the liquid crystal composition forms the liquid crystal layer, and is stably adsorbed in the vicinity of the interface through hydrogen bonding. Simultaneously, the hydrophobic first-chiral compound is repelled and migrates away from the interface. Thus, layer regions dominated by the second-chiral compound and layer regions dominated by the first-chiral compound are gradually formed along the thickness direction of the liquid crystal layer. This results in a cholesteric liquid crystal layered structure with opposite optical rotation directions within the liquid crystal layer, achieving superimposed reflection of light with different optical rotation directions, improving overall reflectivity and display brightness.

[0078] In the above embodiments, the vertically layered structure achieved through hydrophilic-hydrophobic interface effects and hydrogen bonding effects is essentially a dynamic equilibrium structure with relatively limited stability. When the system is subjected to vibration, shear force, or other external disturbances, the already formed layered structure may be disturbed again, causing the first chiral compound and the second chiral compound to remix, resulting in racemization of the system. This weakens or even cancels the reflective effect of the originally formed optically active layered structure, ultimately reducing the selective reflectivity of the cholesteric liquid crystal layer and lowering the overall reflectivity. Based on this, in some embodiments, the raw material components of the cholesteric liquid crystal composition also include a photoinitiator and a polymerizable monomer, wherein the photoinitiator is configured to initiate the polymerization reaction of the polymerizable monomer after irradiation with light of a specific wavelength. By introducing polymerizable monomers into the liquid crystal system, the system can achieve structural locking through photocuring after the layering process is completed.

[0079] Specifically, after the liquid crystal composition is coated to form a liquid crystal film and a certain period of time has elapsed, a stable layered structure has formed within the system due to hydrophilic-hydrophobic interface effects and hydrogen bonding effects. The hydrophilic secondary chiral compound component is enriched in the region near the hydrophilic interface, while the hydrophobic primary chiral compound component is distributed on the side away from the hydrophilic interface. Once this layered structure reaches a stable state, the liquid crystal layer can be irradiated with a specific wavelength light source such as ultraviolet light. This causes the photoinitiator to absorb light energy and generate free radicals, thereby initiating a polymerization reaction of the monomers and forming a cross-linked or network structure within the liquid crystal system. As the polymerization reaction proceeds, the monomers gradually form a stable polymer network structure. This network structure acts as a "skeleton" within the liquid crystal layer, thus fixing the formed layered structure and effectively locking the distribution of different optically active components in the thickness direction. In this way, the stability of the layered structure of the liquid crystal system can be significantly improved, allowing it to maintain its existing optically active distribution structure even under external vibration, mechanical disturbance, or long-term use conditions, thereby avoiding the racemization problem caused by the remixing of the primary and secondary chiral compounds.

[0080] By performing photocuring after the layering is completed, the vertical layered structure formed by the hydrophilic effect and hydrogen bonding effect can be maintained. Although the formed cured structure will cause a slight decrease in reflectivity, it can still maintain a high reflectivity level. A stable structural support network is formed while maintaining the superior optical properties of the liquid crystal. This improves the stability of the system while maintaining its high reflectivity characteristics, which is conducive to further improving the optical performance and long-term reliability of cholesteric liquid crystal displays.

[0081] In some embodiments, the photoinitiator is selected from TPO, DMAP, photoinitiator 907, and photoinitiator 184. These photoinitiators generate free radicals upon exposure to ultraviolet light or light of a specific wavelength, thereby initiating free radical polymerization of the monomers in the system. TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide) exhibits high photoinitiation efficiency and deep photocuring penetration; DMAP (4-dimethylaminopyridine) can serve as a promoter or co-initiating component in the photoinitiation system; photoinitiator 907 (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylacetone) and photoinitiator 184 (1-hydroxycyclohexylphenyl ketone) are commonly used free radical photoinitiators in liquid crystal photopolymerization systems, capable of rapidly generating free radicals and triggering polymerization reactions under ultraviolet light irradiation. By selecting the above photoinitiators, after a stable layered structure is formed in the liquid crystal layer, the polymerization reaction in the system can be rapidly initiated by light irradiation, thereby achieving the fixation of the liquid crystal layered structure.

[0082] In some embodiments, the polymerizing monomers are selected from 2-EHA, TMPTA, PEGMEA, and HEMA. 2-EHA (2-ethylhexyl acrylate) possesses good flexible segment characteristics, enabling the formation of a polymer structure with a certain degree of flexibility after polymerization; TMPTA (trimethylolpropane triacrylate) is a multifunctional monomer capable of forming a three-dimensional network structure with high crosslinking density during polymerization; PEGMEA (polyethylene glycol methyl ether acrylate) has a certain degree of flexible chain structure and good compatibility, which is beneficial for forming a uniformly dispersed polymer network in the liquid crystal system; HEMA (2-hydroxyethyl methacrylate) has hydroxyl functional groups, providing a certain degree of polarity and interfacial stability after polymerization.

[0083] By incorporating the aforementioned polymeric monomers into the cholesteric liquid crystal composition, and using a photoinitiator, the polymerization reaction can be triggered by ultraviolet light irradiation after the liquid crystal system has completed vertical layering. This causes the polymeric monomers to form a polymer network structure within the system. This polymer network can support and lock the already formed layered structure without significantly affecting the optical performance of the liquid crystal, effectively preventing the first and second chiral compounds from remixing during subsequent use, avoiding racemization, and maintaining the liquid crystal layer's reflectivity to light from different optical rotation directions. This further improves the stability and long-term display performance of the cholesteric liquid crystal display structure.

[0084] In some embodiments, the hydrophilic interface can be formed by surface modification of the substrate surface. For example, the hydrophilic interface can be formed by oxygen plasma bombardment, ultraviolet ozone treatment, or by coating the substrate surface with a hydrophilic coating. Through the above treatment methods, hydroxyl groups, carboxyl groups, or other polar functional groups can be introduced into the substrate surface, significantly increasing the surface energy of the substrate surface, thereby forming a hydrophilic interface with good wettability.

[0085] Specifically, when oxygen plasma treatment is used, bombarding the substrate surface with high-energy plasma generates a large number of polar functional groups, such as hydroxyl (–OH) or carboxyl (–COOH) groups, transforming the originally relatively inert substrate surface into a high-surface-energy hydrophilic interface. Similarly, ultraviolet ozone treatment can induce an oxidation reaction on the substrate surface, introducing oxygen-containing functional groups and thus improving surface polarity and wettability. Both of these methods belong to physical or physicochemical surface activation methods, which can improve surface hydrophilicity without significantly altering the overall substrate structure.

[0086] In another embodiment, a hydrophilic interface can also be constructed by coating the substrate surface with a hydrophilic coating. The hydrophilic coating can be a material with polar groups, such as silane coupling agents, polyethylene glycol (PEG) and its derivatives, hydrophilic acrylic resins, or other hydrophilic coating materials. Silane coupling agents typically have silane groups that can chemically bond with the substrate surface and polar end groups that provide hydrophilic properties, thereby forming a stable functionalized layer on the substrate surface. PEG and its derivatives, due to the large number of ether bonds in their molecular chains, have strong hydrophilicity and interfacial wetting ability, and can form a stable hydrophilic layer on the substrate surface. Hydrophilic acrylic resins can be coated and cured to form a coating structure with high surface energy, similarly providing a good hydrophilic interface.

[0087] The hydrophilic interface formed by any of the above methods can provide preferential adsorption sites for hydrophilic secondary chiral compounds in the liquid crystal system, enabling them to form an enriched layer at the interface. At the same time, the adsorption stability of the interface is enhanced through hydrogen bonding or other intermolecular interactions, thereby further promoting the spontaneous stratification of the liquid crystal system in the thickness direction. This is beneficial for constructing a cholesterol-type liquid crystal stratified structure with opposite optical rotation directions.

[0088] In some embodiments, a hydrophilic interface is formed on the side of one of the first and second substrates facing the liquid crystal layer, while a hydrophobic interface is formed on the side of the other substrate facing the liquid crystal layer. By constructing hydrophilic and hydrophobic interfaces at the upper and lower interfaces of the liquid crystal layer respectively, a clear interfacial energy gradient can be formed in the liquid crystal system, thereby further enhancing the directional migration ability of different components in the liquid crystal composition and improving the formation efficiency and stability of spontaneous layering structures.

[0089] Specifically, when a liquid crystal composition is coated between two substrates to form a liquid crystal film, the hydrophilic secondary chiral compounds in the liquid crystal system migrate towards the hydrophilic interface and accumulate in its vicinity, driven by interfacial adsorption and hydrogen bonding at the hydrophilic interface. Simultaneously, the hydrophobic primary chiral compounds are repelled due to the higher interfacial energy with the hydrophilic interface and tend to migrate towards the hydrophobic interface and accumulate in that region due to interfacial matching at the hydrophobic interface. Thus, a hydrophilic interface region dominated by secondary chiral compounds and a hydrophobic interface region dominated by primary chiral compounds are gradually formed along the thickness direction of the liquid crystal layer, thereby constructing a stable upper and lower layered structure. By simultaneously setting hydrophilic and hydrophobic interfaces, a bidirectional layering process can be formed within the liquid crystal system: on the one hand, the hydrophilic interface adsorbs hydrophilic components, exerts an auxiliary driving force on the hydrophilic components under the tendency of hydrogen bonding, and further stabilizes their accumulation after hydrogen bonding; on the other hand, the hydrophobic interface has better interfacial compatibility with hydrophobic components, making it easier for them to form a stable distribution near the interface. This interfacial synergy enables the formation of a clearer and more stable vertical composition gradient within the liquid crystal layer, thereby allowing chiral compounds with different optical rotations to be effectively separated in space.

[0090] In some embodiments, the hydrophobic interface can be formed by surface modification of the substrate surface. For example, the hydrophobic interface can be formed by CF4 plasma bombardment or C4F8 plasma bombardment. These treatments introduce fluorine-containing groups or long-chain hydrophobic structures onto the substrate surface, thereby reducing the surface energy of the substrate surface and forming an interface with strong hydrophobic properties.

[0091] Specifically, when the substrate surface is bombarded with CF4 or C4F8 plasma, the active fluorine radicals in the plasma react with the substrate surface to form a surface rich in –CF4 free radicals. x Modified layers with groups such as –CF2 and –CF3. Due to the extremely low surface energy and strong hydrophobic properties of fluorine-containing groups, the substrate surface can exhibit obvious hydrophobic properties after such plasma treatment, thereby constructing the hydrophobic interface.

[0092] In another embodiment, the hydrophobic interface can also be formed by coating the substrate surface with a hydrophobic coating. The hydrophobic coating can be a fluorosilane coupling agent, a fluorocarbon coating material, a long-chain silane, or other hydrophobic coating materials. For example, fluorosilane coupling agents typically contain silane groups capable of forming chemical bonds with the substrate surface and fluorinated alkyl segments with low surface energy. By forming an ordered monolayer or thin film layer on the substrate surface, the surface energy can be significantly reduced, thereby achieving excellent hydrophobic properties. Fluorocarbon coating materials, due to the large number of C–F bonds in their molecular structure, also provide low surface energy and good chemical stability. Long-chain silanes, by forming an organic layer with long alkyl chains on the substrate surface, give the surface a pronounced hydrophobic property.

[0093] In some embodiments, the first substrate 100 is located on the display side of the reflective liquid crystal display panel relative to the second substrate 200, the hydrophobic interface is located on the side of the first substrate 100 facing the liquid crystal layer 300, and the hydrophilic interface is located on the side of the second substrate 200 facing the liquid crystal layer 300. In other words, the first substrate 100 constitutes the upper interface structure of the display panel structure, while the second substrate 200 constitutes the lower interface structure. With this interface configuration, a layered structure in which the hydrophobic liquid crystal layer 300 and the hydrophilic liquid crystal layer 300 are arranged sequentially from top to bottom can be formed inside the liquid crystal layer 300.

[0094] In this structure, since a hydrophobic interface is formed on one side of the first substrate 100, the hydrophobic first chiral compound and its induced liquid crystal components in the liquid crystal composition preferentially accumulate near this interface, thereby forming an upper cholesteric liquid crystal structure dominated by the first chiral compound on the display side. Simultaneously, the hydrophilic interface formed on one side of the second substrate 200 adsorbs the hydrophilic second chiral compound, causing it to accumulate near this interface and form a lower cholesteric liquid crystal structure. Thus, two liquid crystal structures with opposite optical rotation are formed in the thickness direction of the liquid crystal layer 300, achieving superimposed reflection of light with different optical rotation directions, thereby improving the overall reflectivity and enhancing display brightness. Meanwhile, placing the hydrophobic interface on the first substrate 100 located on the display side has further structural advantages. Since the hydrophobic first chiral compound and the liquid crystal layer 300 formed therein form an enriched layer on the display side, the hydrophobic liquid crystal layer 300 not only performs the function of an optical reflection structure, but also forms a physical barrier layer with low water vapor transmittance. Compared with the hydrophilic liquid crystal region, the hydrophobic liquid crystal layer 300 has a weaker adsorption capacity for water molecules, thereby preventing water vapor in the environment from diffusing to the lower layer through the surface of the display panel to a certain extent.

[0095] Therefore, in this embodiment, the upper hydrophobic liquid crystal layer 300 not only provides optical reflection function, but also serves as a protective barrier to reduce the penetration of water vapor into the lower hydrophilic liquid crystal region, thereby reducing the impact of moisture on the liquid crystal material and interface structure, and further improving the stability and weather resistance of the display device in high humidity or outdoor environments.

[0096] In some embodiments, in a reflective liquid crystal display panel, the raw material components of the cholesterol-type liquid crystal composition, by weight, include: more than 90 parts of nematic liquid crystal, 0.5-5 parts of a first chiral compound, and 0.5-5 parts of a second chiral compound.

[0097] In some embodiments, in a reflective liquid crystal display panel, the raw material components of the cholesterol-type liquid crystal composition, by weight, include: more than 90 parts of nematic liquid crystal, 0.5-5 parts of a first chiral compound, 0.5-5 parts of a second chiral compound, 3-5 parts of a polymeric monomer, and 0.1-0.5 parts of a photoinitiator.

[0098] In some embodiments, the first substrate 100 is disposed above, and the second substrate 200 is disposed below. Preferably, the first substrate 100 adopts a stacked structure of an ITO electrode layer 120 and a carrier substrate 110, wherein the ITO electrode layer 120 is disposed as a transparent conductive layer on the inner surface of the carrier substrate 110 to simultaneously realize the functions of light transmission and electrical signal conduction. The second substrate 200 is preferably a TFT substrate, which integrates a thin-film transistor array circuit. The first substrate 100 and the second substrate 200 are disposed opposite to each other and form a single-cell sealed cavity through a peripheral sealing structure to accommodate the liquid crystal layer 300.

[0099] In this structure, the thin-film transistor array integrated within the TFT substrate provides precise voltage driving signals, thereby enabling fine-tuning of the liquid crystal molecule alignment state and allowing cholesteric liquid crystal to stably switch between planar and focal conical states. The ITO electrode layer 120, as a transparent conductive layer, ensures high light transmittance of the display panel, allowing ambient light to smoothly enter the liquid crystal layer 300 and participate in reflection display, while also effectively conducting driving signals to achieve electric field coordination with the underlying TFT array circuit. Specifically, the ITO electrode layer 120 is a pre-fabricated transparent conductive layer structure, while the electrodes on the inner surface of the TFT substrate are integrally fabricated with the TFT array, thus forming a structure integrating the driving circuit and electrodes, achieving precise driving control of the self-assembled layered liquid crystal in the liquid crystal layer 300.

[0100] In some embodiments, the liquid crystal layer 300 further includes a frame 320. The frame 320 is disposed on the edge region of the surface of the second substrate 200 and can be formed by coating the region with a curable material (e.g., UV-curable epoxy resin). The frame 320 has a dual structural function: on the one hand, the frame 320 can define the filling area of ​​the liquid crystal material, forming a closed liquid crystal cavity when the first substrate 100 and the second substrate 200 are bonded together, thereby preventing the liquid crystal material from overflowing during coating or filling and ensuring that the liquid crystal film 310 is uniformly distributed within the cavity; on the other hand, the frame 320 can also serve as an adhesive layer between the first substrate 100 and the second substrate 200, forming a stable edge sealing structure after curing, thereby ensuring that the single cell cavity has good sealing performance and preventing external air, moisture or impurities from entering the interior of the liquid crystal layer 300.

[0101] In some embodiments, the surface of the second substrate 200 away from the first substrate 100 may also be coated with a light-absorbing layer 400 with a high absorptivity. This light-absorbing layer 400 can be formed of a material with high light absorption capacity, and its main function is to absorb stray light or ambient reflected light from the back of the display panel, thereby reducing interference from non-target light sources on the displayed image. By providing this light-absorbing layer 400, the optical contrast of the display panel can be effectively improved, making the image formed by the cholesteric liquid crystal reflective display clearer and more stable, especially in complex lighting environments or high-brightness environments, further improving the display effect.

[0102] This application also provides a method for preparing a reflective liquid crystal display panel, which is applicable to preparing the reflective liquid crystal display panel described in the foregoing embodiments. The preparation method specifically includes a substrate pretreatment step, a liquid crystal composition preparation step, a single-dispensing and layering process step, and a post-processing step.

[0103] A first substrate and a second substrate are provided through a substrate pretreatment step, and the inner surface of one of the substrates is hydrophilically treated to form a hydrophilic interface and a frame. The raw material components of the cholesteric liquid crystal composition are mixed through a liquid crystal composition preparation step to obtain a uniform and stable liquid crystal composition mixture system. The liquid crystal composition mixture is coated onto the surface of the first substrate or the second substrate through a single drop and layering process to form a liquid crystal film structure. After the liquid crystal film is layered, the first substrate and the second substrate are interlocked through a post-processing step, so that the first substrate and the second substrate are connected by a frame.

[0104] In the substrate pretreatment step, a first substrate and a second substrate are provided and formed respectively. First, the carrier substrate is cleaned to remove surface contaminants and particulate impurities. Subsequently, an ITO electrode layer is deposited on the inner surface of the carrier substrate using a sputtering process, and the ITO electrode layer is patterned to form a transparent conductive electrode structure and constitute a structure as shown in the figure. Figure 7 The first substrate is shown in a′. Simultaneously, the TFT substrate is cleaned to prepare it as shown in the image. Figure 7 The second substrate shown in Figure a is ensured to have a clean and impurity-free inner surface. The inner surface of either the first substrate or one of the second substrates is subjected to a hydrophilic treatment (such as oxygen plasma bombardment, ultraviolet ozone treatment, or coating with a hydrophilic coating) to form a hydrophilic interface, giving it hydrophilic or superhydrophilic properties. If necessary, the inner surface of the other substrate is subjected to a hydrophobic treatment (such as CF4 plasma bombardment, C4F8 plasma bombardment, or coating with a hydrophobic coating) to form a hydrophobic interface, giving it hydrophobic or superhydrophobic properties. Subsequently, as... Figure 7As shown in Figure b, a curable material, such as a UV-curable epoxy resin, is coated around the periphery of a substrate with a hydrophilic interface to form a frame structure for sealing the liquid crystal film.

[0105] In the preparation step of the liquid crystal composition, the raw material components of the cholesterol-type liquid crystal composition are mixed, including nematic liquid crystal, a first chiral compound, a second chiral compound, and optional photoinitiators and polymeric monomers. By rationally selecting the raw material components, a significant difference in hydrophilicity and hydrophobicity is achieved between the chiral components with opposite optical rotation in the system. Subsequently, the mixed system is heated to an isotropic temperature to bring the liquid crystal molecules into an isotropic state, and thorough stirring is performed under this temperature condition to obtain a homogeneous and stable liquid crystal composition mixture system.

[0106] like Figure 7 As shown in Figure c, in the single-drop and layering process, the liquid crystal composition mixture formed above is coated onto the surface of a substrate with a hydrophilic interface using a single-drop method to form a liquid crystal film structure. Subsequently, it is subjected to a static treatment under a temperature-controlled environment. During this process, due to the hydrophilic / hydrophobic differences between the different components in the liquid crystal composition, the hydrophilic components migrate towards the hydrophilic interface and accumulate, while the hydrophobic components are distributed relatively away from the hydrophilic interface. This gradually establishes a significant vertical concentration gradient along the thickness direction of the liquid crystal layer, ultimately forming a liquid crystal film structure as shown in Figure c. Figure 7 The layered structure shown in d.

[0107] In the post-processing steps, such as Figure 7 As shown in Figure e, the first substrate and the second substrate are fastened together, with the ITO electrode layer of the first substrate facing the second substrate, and a sealed liquid crystal cavity is formed by a frame. If a hydrophobic interface is formed on the other substrate, the hydrophobic first chiral compound is repelled due to the high interfacial energy between it and the hydrophilic interface, and tends to migrate towards the hydrophobic side and accumulate in that region under the interfacial matching effect of the hydrophobic interface, making the layered structure formed in the single drop and layering process more stable. If the liquid crystal composition system contains a photoinitiator and polymeric monomers, after a stable layered structure is formed in this stage, the liquid crystal film can be irradiated with a specific wavelength light source such as ultraviolet light, causing the photoinitiator to initiate a polymerization reaction of the polymeric monomers, thereby forming a polymer network structure inside the liquid crystal layer to lock the already formed layered liquid crystal structure. Subsequently, the frame is cured a second time by heating, so that the first substrate and the second substrate are firmly connected by the frame, thereby ensuring the stability and sealing of the overall structure of the display panel. Finally, as Figure 7 As shown in Figure f, a light-absorbing layer with high absorptivity is coated on the surface of the second substrate away from the first substrate to suppress stray light interference from the back side and improve display contrast, thereby completing the fabrication of the reflective liquid crystal display panel.

[0108] The above preparation method enables spontaneous layering of cholesteric liquid crystal systems in the thickness direction through a single drop-and-coat process, avoiding the complex processes required in existing technologies that necessitate separate preparation of left- and right-handed chiral liquid crystal layers followed by physical bonding or secondary coating. This method utilizes the hydrophilicity-hydrophobicity differences between different chiral components in the liquid crystal composition to drive the formation of a stable vertical distribution structure within the system. This allows chiral components with opposite optical rotations to form upper and lower layers within a single-layer liquid crystal film, achieving selective reflection of light in different optical rotation directions without adding additional complex structural layers, thus improving overall reflectivity and display brightness. Furthermore, by introducing a photoinitiator after the layered structure is formed to trigger the curing of the polymer monomers, a stable polymer network structure can be formed within the liquid crystal layer, effectively locking the already formed layered structure. This significantly improves the stability of the liquid crystal system under vibration, bending, or long-term use conditions, avoiding the racemization effect caused by the remixing of chiral components. Compared with existing technologies, this preparation method can not only reduce the complexity of the manufacturing process, reduce production time and cost, but also improve product yield and structural reliability, while obtaining higher reflection efficiency and more stable display performance, so that the reflective liquid crystal display panel still has good visibility and display contrast in outdoor strong light environment.

[0109] Example 1

[0110] A reflective liquid crystal display panel is prepared by the following method.

[0111] Step 1: Substrate Pretreatment. Using a glass substrate as the carrier substrate, the carrier substrate is cleaned to remove surface contaminants and particulate impurities. An ITO electrode layer is deposited on the inner surface of the carrier substrate using a sputtering process, and the ITO electrode layer is patterned to form the first substrate. The TFT substrate is cleaned to serve as the second substrate, ensuring its inner surface is clean and free of impurities. The inner surface of the second substrate is then hydrophilicated by oxygen plasma bombardment to form a hydrophilic interface. Subsequently, a frame structure is formed around the perimeter of the second substrate.

[0112] Step 2: Preparation of the liquid crystal composition. The raw material components of the liquid crystal composition include 96 parts by weight of phenylcyclohexane cyanide liquid crystal PCH-7, 2 parts by weight of dextrorotatory chiral compound perfluoroalkyl modified R1011, and 2 parts by weight of levorotatory chiral compound S1011-OH (shown in Formula 4). After mixing the raw material components of the cholesterol-type liquid crystal composition, heating and stirring thoroughly, a homogeneous and stable liquid crystal composition mixture system is obtained.

[0113] Step 3: Single-drop application and layering process. The liquid crystal composition mixture formed above is coated onto the surface of the second substrate by single-drop application and allowed to stand. A hydrophilic-hydrophobic effect occurs within the system, causing the hydrophilic left-handed chiral compound S1011-OH to migrate and accumulate at the hydrophilic interface, while the hydrophobic right-handed chiral compound R1011 is distributed in the opposite direction. This gradually establishes a vertically layered structure along the thickness direction of the liquid crystal layer, with the upper part dominated by an optically active hydrophobic chiral compound and the lower part dominated by an optically active hydrophilic chiral compound.

[0114] Step 4: Post-processing. After the liquid crystal film is layered, the first substrate is placed on top of the second substrate and fastened together, with the ITO electrode layer of the first substrate facing the second substrate. A sealed liquid crystal cavity is formed by using a frame. The frame is then cured a second time by heating, ensuring a firm connection between the first and second substrates. Finally, black ink is coated onto the surface of the second substrate away from the first substrate to form a light-absorbing layer with high absorption rate.

[0115] When the reflective liquid crystal display panel of this embodiment is exposed to natural light, the maximum reflectivity achievable within the reflection wavelength range is 82.7%. The prepared reflective liquid crystal display panel is placed in a cyclotron oscillator and oscillated at a fixed speed of 150 rpm for 5 minutes, then immediately exposed to natural light. Within the reflection wavelength range, the maximum reflectivity achievable is less than 27%. This is because after oscillation, the two optically active chiral components of the liquid crystal system recombine to form a... Figure 6 The structure shown produces a derotation effect.

[0116] Example 2

[0117] A reflective liquid crystal display panel is prepared using the same method as in Example 1. The difference is that:

[0118] In step two, the raw material components of the liquid crystal composition include 93 parts by weight of phenylcyclohexane cyanide liquid crystal PCH-7, 2 parts by weight of dextrorotatory chiral compound perfluoroalkyl modified R1011, 2 parts by weight of levorotatory chiral compound S1011-OH (shown in Formula 4), 2.9 parts by weight of acrylic monomer 2-EHA, and 0.1 parts by weight of photoinitiator 184.

[0119] Step four also includes: before the frame is cured a second time, the liquid crystal film is irradiated with ultraviolet light so that the photoinitiator 184 initiates the polymerization reaction of the monomer 2-EHA.

[0120] When the reflective liquid crystal display panel of this embodiment is exposed to natural light, the maximum reflectivity obtainable within the reflection wavelength range is 76.4%. The prepared reflective liquid crystal display panel is placed in a gyratory oscillator and oscillated at a fixed speed of 150 rpm for 5 minutes, and then immediately exposed to natural light. Within the reflection wavelength range, the maximum reflectivity obtainable does not show a significant change.

[0121] Example 3

[0122] A reflective liquid crystal display panel is prepared using the same method as in Example 1. The difference is that:

[0123] Step one also includes bombarding the patterned ITO electrode layer surface with CF4 plasma to form a hydrophobic interface.

[0124] When the reflective liquid crystal display panel of this embodiment is exposed to natural light, the maximum reflectivity achievable within the reflection wavelength range is 89.9%. The prepared reflective liquid crystal display panel is placed in a cyclotron oscillator and oscillated at a fixed speed of 150 rpm for 5 minutes, then immediately exposed to natural light. Within the reflection wavelength range, the maximum reflectivity achievable is less than 33%. This is because after oscillation, the two optically active chiral components of the liquid crystal system recombine to form a... Figure 6 The results shown indicate that a racemization effect has occurred.

[0125] Example 4

[0126] A reflective liquid crystal display panel is prepared using the same method as in Example 2. The difference is:

[0127] Step one also includes bombarding the patterned ITO electrode layer surface with CF4 plasma to form a hydrophobic interface.

[0128] When the reflective liquid crystal display panel of this embodiment is exposed to natural light, the maximum reflectivity that can be obtained within the reflection wavelength range is 83.6%. The prepared reflective liquid crystal display panel is placed in a gyratory oscillator and oscillated at a fixed speed of 150 rpm for 5 minutes. Then, it is immediately exposed to natural light. Within the reflection wavelength range, the maximum reflectivity that can be obtained does not change significantly.

[0129] Example 5

[0130] A reflective liquid crystal display panel is prepared by the following method.

[0131] Step 1: Substrate Pretreatment. Using a glass substrate as the carrier substrate, the carrier substrate is cleaned to remove surface contaminants and particulate impurities. An ITO electrode layer is deposited on the inner surface of the carrier substrate using a sputtering process, and the ITO electrode layer is patterned. A PI alignment film wet film is coated onto the surface of the ITO electrode layer using a coating process, and then cured at 200-220℃ for 1 hour to form the upper alignment film. The surface of the upper alignment film is bombarded with C4F8 plasma to form a hydrophobic interface. The carrier substrate, ITO electrode layer, upper alignment film, and hydrophobic interface together constitute the first substrate. The TFT substrate is cleaned to ensure that its inner surface is clean and free of impurities. A PI alignment film wet film is coated onto the surface of the cleaned TFT substrate using a coating process, and then cured at 200-220℃ for 1 hour to form the lower alignment film. The surface of the lower alignment film is hydrophilized by ultraviolet ozone treatment to form a hydrophilic interface. The TFT substrate, lower alignment film, and hydrophilic interface together constitute the second substrate. The upper and lower alignment films are rubbed together to assist in the initial alignment and orientation of liquid crystal molecules, preventing disordered molecular distribution. Subsequently, a frame structure is formed around the periphery of the second substrate.

[0132] Step 2: Preparation of the liquid crystal composition. The raw material components of the liquid crystal composition include 91 parts by weight of dicyclohexane cyanobenzene liquid crystal CCH-4, 2.5 parts by weight of levorotatory chiral compound CB15(S) and 2.5 parts by weight of dextrorotatory chiral compound R811-OH (shown in Formula 1), 3.8 parts by weight of acrylic monomer HEMA and 0.2 parts by weight of photoinitiator DMAP. The raw material components of the cholesterol-type liquid crystal composition are mixed, heated, and thoroughly stirred to obtain a homogeneous and stable liquid crystal composition mixture.

[0133] Step 3: Single-drop application and layering process. The liquid crystal composition mixture formed above is coated onto the surface of the second substrate by single-drop application and allowed to stand. A hydrophilic-hydrophobic effect occurs within the system, causing the hydrophilic right-handed chiral compound R811-OH to migrate and accumulate at the hydrophilic interface, while the hydrophobic left-handed chiral compound CB15(S) is distributed in the opposite direction. This gradually establishes a vertically layered structure along the thickness direction of the liquid crystal layer, with the upper part dominated by an optically active hydrophobic chiral compound and the lower part dominated by an optically active hydrophilic chiral compound.

[0134] Step 4: Post-processing. After the liquid crystal film is layered, the first substrate is placed on top of the second substrate and fastened together, with the hydrophobic interface of the first substrate facing the second substrate. A sealed liquid crystal cavity is formed by using a frame. The liquid crystal film is irradiated with ultraviolet light, causing the photoinitiator DMAP to initiate the polymerization reaction of the monomer HEMA. The frame is then cured a second time by heating, ensuring a firm connection between the first and second substrates through the frame. Finally, black ink is coated on the surface of the second substrate away from the first substrate to form a light-absorbing layer with high absorption rate.

[0135] When the reflective liquid crystal display panel of this embodiment is exposed to natural light, the maximum reflectivity that can be obtained within the reflection wavelength range is 83.1%. The prepared reflective liquid crystal display panel is placed in a gyratory oscillator and oscillated at a fixed speed of 150 rpm for 5 minutes. Then, it is immediately exposed to natural light. Within the reflection wavelength range, the maximum reflectivity that can be obtained does not change significantly.

[0136] Example 6

[0137] A reflective liquid crystal display panel is prepared using the same method as in Example 5. The difference is:

[0138] In step one, the carrier substrate used in the first substrate is a flexible PET substrate, and a fluorosilane coupling agent coating is coated on the surface of the upper alignment layer as a hydrophobic interface. The second substrate uses a flexible TFT substrate, and a polyethylene glycol coating is coated on the surface of the lower alignment layer as a hydrophilic interface.

[0139] In step two, the raw material components of the liquid crystal composition include 91 parts by weight of alkyl cyanobiphenyl liquid crystal 6CB, 2 parts by weight of dextrorotatory chiral compound R811, 2.5 parts by weight of levorotatory chiral compound S811-OH (shown in Formula 2), 4.3 parts by weight of acrylic monomer PEGMEA and 0.2 parts by weight of photoinitiator TPO.

[0140] When the reflective liquid crystal display panel of this embodiment is exposed to natural light, the maximum reflectivity obtainable within the reflection wavelength range is 79.8%. The prepared reflective liquid crystal display panel is placed in a gyratory oscillator and oscillated at a fixed speed of 150 rpm for 5 minutes, and then immediately exposed to natural light. Within the reflection wavelength range, the maximum reflectivity obtainable does not show a significant change.

[0141] Example 7

[0142] A reflective liquid crystal display panel is prepared by the following method.

[0143] Step 1: Substrate Pretreatment. Using a glass substrate as the carrier substrate, the carrier substrate is cleaned to remove surface contaminants and particulate impurities. An ITO electrode layer is deposited on the inner surface of the carrier substrate using a sputtering process, and the ITO electrode layer is patterned. A PI alignment film wet film is coated on the surface of the ITO electrode layer using a coating process, and then cured at 200-220℃ for 1 hour to form the upper alignment film. A silane coupling agent coating is applied to the surface of the upper alignment film to form a hydrophilic interface. The carrier substrate, ITO electrode layer, upper alignment film, and hydrophilic interface together constitute the first substrate. The TFT substrate is cleaned to ensure that its inner surface is clean and free of impurities. A PI alignment film wet film is coated on the surface of the cleaned TFT substrate using a coating process, and then cured at 200-220℃ for 1 hour to form the lower alignment film. The surface of the lower alignment film is hydrophobically treated with a fluorocarbon material coating to form a hydrophobic interface. The TFT substrate, lower alignment film, and hydrophobic interface together constitute the second substrate. The upper and lower alignment films are rubbed together to assist in the initial alignment and orientation of liquid crystal molecules, preventing disordered molecular distribution. Subsequently, a frame structure is formed around the periphery of the first substrate.

[0144] Step 2: Preparation of the liquid crystal composition. The raw material components of the liquid crystal composition include 94 parts by weight of liquid crystal BL006, 2 parts by weight of dextrorotatory chiral compound CB15(R), 2 parts by weight of levorotatory chiral compound S811-OH (shown in Formula 2), 1.9 parts by weight of acrylic monomer 2-EHA, and 0.1 parts by weight of photoinitiator TPO. The raw material components of the cholesterol-type liquid crystal composition are mixed, heated, and thoroughly stirred to obtain a homogeneous and stable liquid crystal composition mixture.

[0145] Step 3: Single-drop application and layering process. The liquid crystal composition mixture formed above is applied to the surface of the first substrate by single-drop application and allowed to stand. A hydrophilic-hydrophobic effect occurs within the system, causing the hydrophilic left-handed chiral compound S811-OH to migrate and accumulate at the hydrophilic interface, while the hydrophobic right-handed chiral compound CB15(R) is distributed in the opposite direction. This gradually establishes a vertically layered structure in the thickness direction of the liquid crystal layer, with the upper part dominated by an optically active hydrophobic chiral compound and the lower part dominated by an optically active hydrophilic chiral compound.

[0146] Step 4: Post-processing. After the liquid crystal film is layered, the second substrate is placed on top of the first substrate and fastened together, with the hydrophobic interface of the second substrate facing the first substrate. A sealed liquid crystal cavity is formed by using a frame. The liquid crystal film is irradiated with ultraviolet light, causing the photoinitiator TPO to initiate the polymerization reaction of the monomer 2-EHA. The frame is then cured a second time by heating, ensuring a firm connection between the first and second substrates through the frame. Finally, black ink is coated on the side of the second substrate away from the first substrate to form a light-absorbing layer with high absorption rate.

[0147] When the reflective liquid crystal display panel of this embodiment is exposed to natural light, the maximum reflectivity obtainable within the reflection wavelength range is 80.4%. The prepared reflective liquid crystal display panel is placed in a gyratory oscillator and oscillated at a fixed speed of 150 rpm for 5 minutes, and then immediately exposed to natural light. Within the reflection wavelength range, the maximum reflectivity obtainable does not show significant change.

[0148] This application also provides a reflective liquid crystal display device, which includes the reflective liquid crystal display panel provided in the foregoing embodiments of this application. This reflective liquid crystal display device is preferably an electronic paper display and can be applied to e-book readers, electronic tags, electronic whiteboards, and commercial billboards, etc. Since the reflective liquid crystal display device disclosed in this application includes the reflective liquid crystal display panel provided in the above embodiments, the reflective liquid crystal display device having this reflective liquid crystal display panel also has all the above-mentioned technical effects, which will not be described in detail here. Other components, principles, and manufacturing methods of the reflective liquid crystal display panel and the reflective liquid crystal display device are known to those skilled in the art and will not be described in detail here.

[0149] Some embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0150] The above are merely specific embodiments of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A reflective liquid crystal display panel, characterized by comprising: It includes a first substrate, a liquid crystal layer, and a second substrate stacked sequentially, wherein the liquid crystal layer comprises a liquid crystal film made of a cholesteric liquid crystal composition; The raw material components of the cholesterol-type liquid crystal composition include nematic liquid crystal, a hydrophobic first chiral compound, a hydrophilic second chiral compound, a photoinitiator, and a polymeric monomer. The first chiral compound and the second chiral compound have opposite optical rotations. The photoinitiator is configured to initiate a polymerization reaction of the polymeric monomer upon exposure to light. A hydrophilic interface is formed on the side of the first substrate and the second substrate facing the liquid crystal layer.

2. The reflective liquid crystal display panel according to claim 1, characterized in that, The first chiral compound is selected from at least one of R811, S811, CB15 (S), CB15 (R), R1011 and S1011.

3. The reflective liquid crystal display panel according to claim 1, characterized in that, The second chiral compound is selected from at least one of R811-OH, S811-OH, R1011-OH, S1011-OH, dihydroxyl-modified chiral compounds, polyoxyethylene ether-modified chiral compounds, and carboxyl-modified chiral compounds.

4. The reflective liquid crystal display panel according to claim 1, characterized in that, The photoinitiator is selected from at least one of TPO, DMAP, photoinitiator 907 and photoinitiator 184; the polymer monomer is selected from at least one of 2-EHA, TMPTA, PEGMEA and HEMA.

5. The reflective liquid crystal display panel according to claim 1, characterized in that, The hydrophilic interface is formed by bombarding the surface of the substrate with oxygen plasma, by treating the surface of the substrate with ultraviolet ozone, or by coating with a hydrophilic coating.

6. The reflective liquid crystal display panel according to any one of claims 1-5, characterized in that, A hydrophobic interface is formed on the side of the first substrate and the second substrate facing the liquid crystal layer.

7. The reflective liquid crystal display panel according to claim 6, characterized in that, The hydrophobic interface is formed by bombarding the surface of the substrate with CF4 plasma, bombarding the surface of the substrate with C4F8 plasma, or by coating with a hydrophobic coating.

8. The reflective liquid crystal display panel according to claim 6, characterized in that, The first substrate is located on the display side of the reflective liquid crystal display panel relative to the second substrate, the hydrophobic interface is located on the side of the first substrate facing the liquid crystal layer, and the hydrophilic interface is located on the side of the second substrate facing the liquid crystal layer.

9. A method for preparing a reflective liquid crystal display panel, used to prepare the reflective liquid crystal display panel as described in any one of claims 1-8, characterized in that, include: A first substrate and a second substrate are provided respectively, and the inner surface of one of the substrates is hydrophilized to form a hydrophilic interface and a glue frame. The raw material components of the cholesterol-type liquid crystal composition are mixed to obtain a uniform and stable liquid crystal composition mixing system; A liquid crystal composition mixture is coated onto the surface of a first substrate or a second substrate to form a liquid crystal thin film structure. The first substrate and the second substrate are fastened together so that the first substrate and the second substrate are connected by a glue frame.

10. A reflective liquid crystal display device, characterized in that, Including the reflective liquid crystal display panel as described in any one of claims 1-8.

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