Electronic paper, method for manufacturing electronic paper, and display device

Abstract

This invention provides electronic paper, a method for preparing electronic paper, and a display device, relating to the field of display device technology. The electronic paper includes a first substrate assembly and a second substrate assembly disposed opposite to each other, with a plurality of pixel units disposed between the first substrate assembly and the second substrate assembly. Each pixel unit contains a liquid crystal layer, and each liquid crystal layer contains a photoluminescent material. This electronic paper can reuse the portion of incident light that has been transmitted, effectively improving light utilization and display brightness.

Description

Technical Field

[0001] This invention relates to the field of electronic paper technology, and in particular to an electronic paper, a method for preparing electronic paper, and a display device. Background Technology

[0002] Cholesteric liquid crystal electronic paper (CLC) holds a significant position in reflective display technology due to its unique bistable properties and the advantage of achieving full-color display without the need for color filters. However, Cholesteric CLC has long faced the core problem of low light reflectivity in practical applications. Limited by the display principle itself, the theoretical maximum reflectivity of incident light in a planar state is generally no more than 50%. In actual devices, due to factors such as optical absorption of the liquid crystal material, transmission loss of the substrate and electrodes, and polarization-selective reflection, the overall reflectivity is often even lower, typically only around 20% to 30%. This low reflectivity directly results in a darker display image and insufficient brightness, while also limiting further improvements in display contrast, affecting image depth and color saturation. Therefore, how to effectively improve the light reflectivity of Cholesteric CLC while maintaining its inherent color performance and bistable properties has become a crucial technical challenge that urgently needs to be addressed in this field.

[0003] Therefore, it is necessary to provide a new electronic paper, a method for preparing electronic paper, and a display device to solve or at least alleviate the above-mentioned technical defects. Summary of the Invention

[0004] The main objective of this invention is to provide electronic paper, a method for preparing electronic paper, and a display device, aiming to solve the technical problems of low light utilization and low display brightness in existing electronic paper.

[0005] To achieve the above objectives, according to some embodiments of this application, this application provides an electronic paper, including a first substrate assembly and a second substrate assembly disposed opposite to each other, a plurality of pixel units disposed between the first substrate assembly and the second substrate assembly, a liquid crystal layer disposed in each pixel unit, and a photoluminescent material disposed in each liquid crystal layer.

[0006] In some embodiments, the photoluminescent material is dispersed within the liquid crystal layer.

[0007] In some embodiments, the plurality of pixel units include a variety of sub-pixels, and the number of types of photoluminescent materials is set to correspond to the number of types of sub-pixels. A portion of the incident light is reflected on the surface of the liquid crystal layer, and the photoluminescent material can be excited by another portion of the light transmitted into the liquid crystal layer, thereby emitting light corresponding to the sub-pixel.

[0008] In some embodiments, in each pixel unit, the mass fraction of the liquid crystal layer is 85% to 95%, the mass fraction of the photoluminescent material is 0.5% to 10%, and the photoluminescent material is uniformly distributed in the liquid crystal layer.

[0009] In some embodiments, black charged particles are disposed within the liquid crystal layer. These black charged particles can move under the influence of the electric fields of the first substrate assembly and the second substrate assembly to control the display brightness of the corresponding pixel unit.

[0010] In some embodiments, the first substrate assembly includes an array substrate and a first electrode layer, the second substrate assembly includes a color filter substrate and a second electrode layer, and the first electrode layer and the second electrode layer are disposed opposite to each other; the electronic paper further includes a third electrode layer, the third electrode layer is disposed between the first electrode layer and the second electrode layer, the third electrode layer and the first electrode layer form a first electric field region, and the third electrode layer and the second electrode layer form a second electric field region.

[0011] In some embodiments, the third electrode layer includes a mesh plate having a plurality of mesh holes.

[0012] In some embodiments, the shape of the mesh is one or more of the following: circular, square, hexagonal, or elliptical.

[0013] According to some embodiments of this application, this application provides a method for preparing electronic paper, the method comprising the following steps: Place the cholesterol liquid crystal in a hot bath at a preset temperature; Black charged particles and photoluminescent material are added to the cholesterol liquid crystal and mixed evenly. A first substrate assembly is provided, and a barrier is provided on the first substrate assembly to define a plurality of pixel spaces; The well-mixed solution is added to the corresponding pixel space according to the type of photoluminescent material; Encapsulate the second substrate assembly.

[0014] According to some embodiments of this application, this application provides a method for preparing electronic paper, the method comprising the following steps: A first electrode layer and a first photoresist layer are sequentially disposed on an array substrate, and the first photoresist layer is exposed; an intermediate electrode layer and a second photoresist layer are sequentially disposed on the first photoresist layer. The second photoresist layer is exposed and developed to etch multiple mesh holes on the intermediate electrode layer to form the third electrode layer, and the second photoresist layer is removed. A third photoresist layer is disposed on the third electrode layer, and the third photoresist layer is exposed; wherein, the first photoresist layer and the third photoresist layer are exposed using the same photomask; The first photoresist layer and the third photoresist layer are developed to leave multiple spaced baffles, which define multiple pixel spaces. A liquid crystal mixing solution is added to each pixel space; the liquid crystal mixing solution includes cholesterol liquid crystal and photoluminescent material and black charged particles dispersed in the cholesterol liquid crystal; Encapsulate the second substrate assembly.

[0015] According to some embodiments of this application, this application provides a display device, the display device including the electronic paper described above.

[0016] In the above scheme, the electronic paper includes a first substrate assembly and a second substrate assembly arranged opposite to each other. Multiple pixel units are disposed between the first substrate assembly and the second substrate assembly. Each pixel unit contains a liquid crystal layer, and each liquid crystal layer contains a photoluminescent material. This invention enables the secondary utilization of the transmitted portion of incident light, effectively improving light utilization and display brightness. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a cross-sectional structural diagram of the electronic paper according to an embodiment of the present invention; Figure 2 This is a schematic diagram of an optical path structure of the electronic paper according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of electronic paper containing black charged particles in one state according to an embodiment of the present invention; Figure 4 This is a schematic diagram of another state of electronic paper containing black charged particles according to an embodiment of the present invention; Figure 5 This is a schematic diagram of another state of electronic paper containing black charged particles according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of an electronic paper containing a third electrode layer in one state according to an embodiment of the present invention; Figure 7 This is a schematic diagram of another state of electronic paper containing a third electrode layer according to an embodiment of the present invention; Figure 8 This is a schematic diagram of another state of electronic paper containing a third electrode layer according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of the third electrode layer of the electronic paper according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the structure of the third electrode layer of the electronic paper according to an embodiment of the present invention; Figure 11 This is a schematic flowchart of a method for manufacturing electronic paper according to an embodiment of the present invention; Figure 12 for Figure 11 A schematic diagram illustrating the structural changes during the manufacturing process; Figure 13 for Figure 11 A schematic diagram illustrating the structural changes during the manufacturing process; Figure 14 for Figure 11 A schematic diagram illustrating the structural changes during the manufacturing process; Figure 15 This is another schematic diagram of the manufacturing method of electronic paper according to an embodiment of the present invention; Figure 16 for Figure 15 A schematic diagram illustrating the structural changes during the manufacturing process; Figure 17 for Figure 15 A schematic diagram illustrating the structural changes during the manufacturing process; Figure 18 for Figure 15 A schematic diagram illustrating the structural changes during the manufacturing process; Figure 19 for Figure 15 A schematic diagram illustrating the structural changes during the manufacturing process; Figure 20 for Figure 15 A schematic diagram of structural changes during the manufacturing process.

[0019] Label Explanation: 100. Electronic paper; 1. Liquid crystal layer; 2. First substrate assembly; 21. Array substrate; 22. First electrode layer; 3. Second substrate assembly; 31. Color filter substrate; 32. Second electrode layer; 4. Photoluminescent material; 5. Subpixel; 6. Black charged particle; 7. Third electrode layer; 71. Mesh; 8. First electric field region; 9. Second electric field region; 10. Barrier; 11. Pixel space; 200, First photoresist layer; 300, Second photoresist layer; 400, Intermediate electrode layer; 500, Photomask.

[0020] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that all directional indications in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0023] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0024] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0025] Cholesterol liquid crystal is a liquid crystal material with a helical molecular arrangement. When the pitch of its molecular arrangement satisfies the Bragg reflection condition with the wavelength of the incident light, it can selectively reflect circularly polarized light of a specific wavelength, exhibiting vibrant colors. In the planar state, the liquid crystal molecules are arranged in an ordered helical pattern, reflecting light of a specific color; in the focal conic state, the liquid crystal molecules become disordered, mainly exhibiting light scattering or weak transmission, appearing as a dark or semi-transparent state. By applying a suitable electric field pulse, cholesterol liquid crystal can reversibly switch between these two states, thereby achieving bistable reflective displays.

[0026] However, the display principle of cholesteric liquid crystal electronic paper inherently limits its utilization of incident light. Specifically, for any given sub-pixel, the cholesteric liquid crystal can only reflect light in a specific wavelength corresponding to the color of that sub-pixel; light in other wavelengths will directly transmit through the liquid crystal layer and be absorbed by the back coating at the bottom. Taking RGB three-color sub-pixels as an example, each sub-pixel reflects only about one-third of the incident light energy, with the remaining two-thirds being wasted. In related technologies, although some improvements have been proposed, such as adding a metal reflective layer or a high-refractive-index dielectric mirror to the back of the liquid crystal layer to attempt to reuse the transmitted light, or by optimizing the birefringence parameters of the liquid crystal material and adjusting the pitch distribution to broaden the reflection bandwidth, these methods often have significant limitations: the introduction of a metal reflective layer may introduce additional absorption losses and color shift; broadening the reflection bandwidth will reduce color purity; and multi-layer stacked structures will lead to increased device thickness, significantly increased process complexity, and higher costs.

[0027] Through in-depth research, the applicant noted that the fundamental reason for the low reflectivity of cholesteric liquid crystal electronic paper is that it only utilizes the energy of the incident light that is selectively reflected, while the transmitted light energy is completely wasted. In other words, if this previously wasted transmitted light energy could also be utilized, it is hoped that the light utilization rate of electronic paper can be fundamentally improved. Based on this understanding, the applicant proposed dispersing photoluminescent materials within the cholesteric liquid crystal layer—when unreflected light enters the liquid crystal layer, the dispersed photoluminescent materials can be excited by the transmitted light, emitting light corresponding to the color of the sub-pixel, thereby converting the previously wasted transmitted light into effective display light output, thus improving light utilization and display brightness.

[0028] Therefore, this application provides an electronic paper.

[0029] Reference Figure 1 According to some embodiments of this application, this application provides an electronic paper 100, including a first substrate assembly 2 and a second substrate assembly 3 disposed opposite to each other, a plurality of pixel units disposed between the first substrate assembly 2 and the second substrate assembly 3, a liquid crystal layer 1 disposed in each pixel unit, and a photoluminescent material 4 disposed in each liquid crystal layer 1.

[0030] The first substrate assembly 2 and the second substrate assembly 3 are disposed opposite to each other, forming a receiving space between them. Multiple pixel units are disposed within this receiving space, each pixel unit being independent and separated from each other by a barrier 10 or a similar isolation structure. Each pixel unit contains a liquid crystal layer 1, which is made of cholesteric liquid crystal material. A photoluminescent material 4 is disposed within each liquid crystal layer 1. It should be noted that the photoluminescent material 4 is physically distributed within the cholesteric liquid crystal material, i.e., within the liquid crystal layer 1; no new compound is formed between the two, but rather they remain in a physically blended state. The photoluminescent material 4 is a functional material capable of absorbing light energy of a specific wavelength and converting it into light energy of different wavelengths for emission. Its light emission process typically includes three stages: photon absorption, energy transfer, and light emission.

[0031] Reference Figure 2 When incident light shines on the liquid crystal layer 1, the cholesteric liquid crystal selectively reflects light of a specific wavelength corresponding to the pitch, while light of other wavelengths is transmitted into the interior of the liquid crystal layer 1. The photoluminescent material 4 dispersed within the liquid crystal layer 1 absorbs the energy of this transmitted light, is excited, and emits light of the corresponding wavelength, thereby converting the originally wasted transmitted light into effective display light output. For example, if the corresponding sub-pixel 5 is blue, then by selecting the type of photoluminescent material 4, the photoluminescent material 4 disposed within the liquid crystal layer 1 absorbs the transmitted light and is excited to emit blue light. Similarly, if the corresponding sub-pixel 5 is red, then by selecting the type of photoluminescent material 4, the photoluminescent material 4 disposed within the liquid crystal layer 1 absorbs the transmitted light and is excited to emit red light; the same principle applies if the corresponding sub-pixel 5 is green. Compared to the conventional cholesteric liquid crystal electronic paper 100 without the addition of photoluminescent material 4, the electronic paper 100 of this embodiment can reuse the portion of the incident light that is transmitted, effectively improving the light utilization rate and display brightness.

[0032] Reference Figure 1 and Figure 2 In some embodiments, the photoluminescent material is dispersed within the liquid crystal layer.

[0033] Photoluminescent material 4 is physically blended and dispersed in the liquid crystal layer 1 composed of cholesteric liquid crystal material. Specifically, during the preparation of electronic paper 100, photoluminescent material 4 and cholesteric liquid crystal material are mixed in a preset ratio, and the photoluminescent material 4 is uniformly dispersed in the cholesteric liquid crystal material by means of mechanical stirring, ultrasonic dispersion, or high-speed shearing to form a stable blend system. No new compounds are formed between photoluminescent material 4 and cholesteric liquid crystal material; instead, they remain in a physically blended state, with photoluminescent material 4 uniformly distributed as the dispersed phase in the cholesteric liquid crystal material, which is the continuous phase.

[0034] In some further embodiments, the dispersion can be uniformly dispersed within the liquid crystal layer 1. This uniform dispersion of the photoluminescent material 4 throughout the entire liquid crystal layer 1 allows light transmitted into the liquid crystal layer 1 to encounter the photoluminescent material 4 as many times as possible along its propagation path, increasing the contact probability between the photoluminescent material 4 and the transmitted light. This results in more efficient absorption of transmitted light energy and its conversion into effective display light output, further improving light utilization and display brightness. Furthermore, the dispersed arrangement effectively prevents excessive aggregation of the photoluminescent material 4 in localized areas. If the photoluminescent material 4 agglomerates, the luminescent centers within the agglomerates will experience concentration quenching due to the short energy transfer distance. Simultaneously, the agglomerates will absorb photons emitted by themselves or neighboring luminescent centers, leading to a decrease in the luminescence quantum yield. Through dispersion, particularly uniform dispersion, maintaining appropriate spacing between the photoluminescent material particles significantly reduces self-absorption and quenching effects, ensuring a high photoluminescence quantum yield. Furthermore, when the photoluminescent material 4 is dispersed in the continuous phase of the cholesteric liquid crystal in the form of microparticles or molecules, and the dispersion is uniform and the particle size is controlled within a suitable range (e.g., 0.05–5 μm, quantum dot particle size 1–100 nm), its interference with the helical structure and molecular orientation of the cholesteric liquid crystal is minimal. This ensures that the selective reflectance characteristics and electro-optic response performance of the liquid crystal layer 1 are not compromised, thus guaranteeing that the display contrast and color saturation of the electronic paper 100 remain unaffected. Additionally, the uniform dispersion of the photoluminescent material 4 in each pixel unit (e.g., sub-pixel 5) ensures consistent luminous intensity at all locations within the entire pixel unit, preventing uneven brightness or color deviation within the pixel due to local concentration differences. For multiple sub-pixels of different colors, uniform dispersion guarantees stable color performance for each sub-pixel, resulting in a uniform and clear overall image display.

[0035] Reference Figure 1 and Figure 2 In some embodiments, multiple pixel units include multiple sub-pixels 5, and the number of types of photoluminescent materials 4 is set to correspond to the number of types of sub-pixels 5. Part of the incident light is reflected on the surface of the liquid crystal layer 1, and the photoluminescent materials 4 can be excited by another part of the light transmitted into the liquid crystal layer 1, thereby emitting light corresponding to the sub-pixel 5.

[0036] Multiple pixel units include various sub-pixels 5, such as red sub-pixels 5, green sub-pixels 5, and blue sub-pixels 5. These three types of sub-pixels 5 together constitute a complete pixel unit. The number of types of photoluminescent materials 4 is set corresponding to the number of types of sub-pixels 5. For example, if there are three types of sub-pixels 5, there are also three types of photoluminescent materials 4. Each sub-pixel 5 contains one type of photoluminescent material 4. For instance, the liquid crystal layer 1 of the red sub-pixel 5 contains a red photoluminescent material 4 that emits red light when excited; the liquid crystal layer 1 of the green sub-pixel 5 contains a green photoluminescent material 4 that emits green light when excited; and the liquid crystal layer 1 of the blue sub-pixel 5 contains a blue photoluminescent material 4 that emits blue light when excited. When incident light shines on the liquid crystal layer 1, some of the light undergoes selective reflection on the surface of the liquid crystal layer 1—the red sub-pixel 5 reflects red light, the green sub-pixel 5 reflects green light, and the blue sub-pixel 5 reflects blue light—thus presenting the corresponding colors. Another portion of the light penetrates into the liquid crystal layer 1. This transmitted light contains components of various wavelengths. The wavelengths that can be absorbed by the photoluminescent material 4 will excite the photoluminescent material 4, causing it to emit light corresponding to the color of the sub-pixel 5. Taking the red sub-pixel 5 as an example, in the incident light, except for the red band which is reflected by the liquid crystal layer 1, the other wavelengths of light penetrate into the liquid crystal layer 1 and excite the red photoluminescent material 4 to emit red light, thereby increasing the total red light output of the red sub-pixel 5. It is worth mentioning that because the light emitted by the photoluminescent material 4 can have a narrower half-width, the red color it exhibits is purer. Therefore, it can enhance color performance while improving light utilization.

[0037] In some embodiments, in each pixel unit, the mass fraction of the liquid crystal layer 1 is 85% to 95%, the mass fraction of the photoluminescent material 4 is 0.5% to 10%, and the photoluminescent material 4 is uniformly distributed in the liquid crystal layer 1.

[0038] The mass ratio of liquid crystal layer 1 and photoluminescent material 4 in each pixel unit needs to meet a certain range to ensure a balance between display effect and light utilization. The mass fraction of liquid crystal layer 1 is 85% to 95%, and the mass fraction of photoluminescent material 4 is 0.5% to 10%. In a further embodiment, the mass fraction of liquid crystal layer 1 is 94% to 96%, and the mass fraction of photoluminescent material 4 is 2% to 5%. The remaining components are: 0.5% to 8% of black charged particles, used to control dark-state shading and grayscale; 0.1% to 2% of stabilizer and dispersant, used to prevent particle aggregation and improve suspension stability; and 0.5% to 2% of polymerizable monomer, used to form a sparse polymer network and anchor the dispersion state. If the content of photoluminescent material 4 is too low, the brightening effect will be insignificant and the light utilization rate cannot be effectively improved; if the content of photoluminescent material 4 is too high, it may enhance the scattering effect, affect the orientation order of liquid crystal molecules, and reduce reflectivity. The photoluminescent material 4 is uniformly distributed in the liquid crystal layer 1, which ensures that transmitted light can be uniformly absorbed and converted throughout the entire sub-pixel 5 area, avoiding local bright spots or dark areas caused by uneven distribution of the photoluminescent material 4. Uniform distribution can be achieved by thoroughly mixing the photoluminescent material 4 with cholesteric liquid crystal, for example, by using low-shear stirring combined with ultrasonic-assisted dispersion, so that the photoluminescent material 4 is uniformly suspended in the liquid crystal material in the form of tiny particles.

[0039] Reference Figures 3 to 5 In some embodiments, black charged particles 6 are disposed in the liquid crystal layer 1. The black charged particles 6 can move under the action of the electric fields of the first substrate assembly 2 and the second substrate assembly 3 to control the display brightness of the corresponding pixel unit.

[0040] The aforementioned embodiment may have some phenomena by setting the photoluminescent material 4 in the liquid crystal layer 1. That is, when the screen needs to display black, the cholesteric liquid crystal is in a state that allows all light to pass through. The transmitted light will excite the photoluminescent material 4 to produce undue light emission, resulting in the dark state not being completely darkened and the contrast decreasing.

[0041] To resolve this contradiction, the applicant further incorporates charged black particles 6 into the liquid crystal layer 1. Specifically, the liquid crystal layer 1 also contains charged black particles 6. The charged black particles 6 refer to black particulate material with a static charge on its surface, which can move directionally under the influence of an electric field. Electrode layers are respectively disposed on the first substrate assembly 2 and the second substrate assembly 3. When voltages of different polarities are applied between the two electrode layers, a directionally controllable electric field is formed. The charged black particles 6 carry a specific charge polarity and move towards the electrode with the opposite charge polarity under the influence of the electric field. By controlling the direction of the electric field applied between the first substrate assembly 2 and the second substrate assembly 3, it is possible to control whether the charged black particles 6 accumulate in the liquid crystal layer 1 closer to the first substrate assembly 2 or closer to the second substrate assembly 3. When the black charged particles 6 gather at different positions in the liquid crystal layer 1, their degree of blocking of incident light varies—when they gather near the light-incident side, they can absorb the incident light in advance, making the pixel unit appear dark; when they gather far from the light-incident side, they block the incident light less, allowing the pixel unit to display the bright state normally. For example... Figure 3 This indicates that the black charged particles 6 are controlled to gather in the liquid crystal layer 1 on the side close to the first substrate assembly 2. Figure 4 This means that the black charged particles 6 of different pixel units are respectively concentrated on the side close to the first substrate assembly 2 or the side close to the second substrate assembly 3, thereby realizing light entering from different sides of different pixel units. Figure 5 The black charged particles 6 controlling each pixel unit are respectively disposed on both sides, realizing a novel grayscale adjustment mechanism based on the spatial concentration gradient of the black charged particles 6. By controlling the spatial position of the black charged particles 6 through an electric field, the display brightness of the corresponding pixel unit can be effectively controlled, realizing the adjustment from bright to dark states and different grayscale levels. In addition, the introduction of black charged particles 6 can replace the traditional back coating structure, providing a prerequisite for realizing double-sided display. In the liquid crystal layer 1, the mass fraction of black charged particles 6 can be 0.5% to 8%, and in a further embodiment, the mass fraction of liquid crystal layer 1 is 1% to 3%.

[0042] Reference Figures 6 to 8 In some embodiments, the first substrate assembly 2 includes an array substrate 21 and a first electrode layer 22, and the second substrate assembly 3 includes a color filter substrate 31 and a second electrode layer 32, with the first electrode layer 22 and the second electrode layer 32 facing each other; the electronic paper 100 also includes a third electrode layer 7, which is disposed between the first electrode layer 22 and the second electrode layer 32, and the third electrode layer 7 and the first electrode layer 22 form a first electric field region 8, and the third electrode layer 7 and the second electrode layer 32 form a second electric field region 9.

[0043] The first substrate assembly 2 includes an array substrate 21 and a first electrode layer 22 disposed on the array substrate 21. The array substrate 21 may be a thin-film transistor array substrate 21, used to independently apply driving signals to each pixel unit. The second substrate assembly 3 includes a color filter substrate 31 and a second electrode layer 32 disposed on the color filter substrate 31. The color filter substrate 31 may have a color filter layer or a black matrix structure. The first electrode layer 22 and the second electrode layer 32 are arranged facing each other, forming a pixel unit space for accommodating the liquid crystal layer 1 between them. The electronic paper 100 also includes a third electrode layer 7, which is disposed between the first electrode layer 22 and the second electrode layer 32, dividing the single electric field region originally defined by the first electrode layer 22 and the second electrode layer 32 into two electric field regions—a first electric field region 8 is formed between the third electrode layer 7 and the first electrode layer 22, and a second electric field region 9 is formed between the third electrode layer 7 and the second electrode layer 32. By applying different voltages to the first electrode layer 22, the third electrode layer 7, and the second electrode layer 32, electric fields with the same or opposite directions can be formed in the first electric field region 8 and the second electric field region 9, respectively.

[0044] Reference Figure 6 When a third electrode layer 7 is added in the middle, during single-sided display, the third electrode layer 7 can be given a momentary voltage to attract the black charged particles 6 at the bottom to the third electrode layer 7. Since the third electrode layer 7 is close to the first electrode layers 22 and the second electrode layers 32 on both sides, it can attract the black charged particles 6 to move quickly. After moving to the third electrode layer 7, the second electrode layer 32 has a greater voltage, which will attract the black charged particles 6 upwards. Because the path length at both ends is greatly shortened, the black charged particles 6 will maintain high-speed movement, thus significantly reducing the migration time. Furthermore, by adjusting the voltage difference between the third electrode layer 7 and the first electrode layers 22 and the second electrode layers 32, various electric field gradients can be formed in the liquid crystal layer 1. This can drive the black charged particles 6 to any height in the vertical direction, forming a continuous distribution from "completely gathered at the top" to "completely gathered at the bottom." Figure 6 The black charged particles 6 are completely gathered at the bottom. Figure 7 The black charged particles 6 are completely concentrated at the top. As the particle distribution changes, the area and density of light reflected from the liquid crystal layer 1 also change continuously, thus achieving continuous grayscale. It is worth noting that the presence of the third electrode layer 7 also allows different images to be displayed on each side of the double-sided display without sacrificing the original resolution, greatly improving the display effect of the double-sided display. In this embodiment, since the third electrode layer 7 is located in the middle of the liquid crystal layer 1, the distance the black charged particles 6 travel from one electrode to the third electrode layer 7 is only half that from one electrode to the other, thus significantly shortening the migration path of the black charged particles 6 and improving the response speed.

[0045] Reference Figure 9 and Figure 10 In some embodiments, the third electrode layer 7 is a mesh plate with multiple mesh holes 71.

[0046] The third electrode layer 7 adopts a grid plate structure, meaning that multiple mesh holes 71 are formed on the third electrode layer 7. This grid plate structure creates a perforated electrode network within the liquid crystal layer 1—the electrode material forms the grid's outline, while the mesh hole areas 71 are not covered by electrode material. This structural design ensures that the third electrode layer 7 can function as the third electrode layer, regulating the electric field and attracting black charged particles 6, while also ensuring that light can pass through the mesh hole areas 71 and propagate normally within the liquid crystal layer 1. If the third electrode layer 7 used a continuous electrode structure across its entire surface, it would block light transmission, affecting the display effect. The grid plate structure, however, provides a light propagation channel through the mesh holes 71, ensuring that the placement of the third electrode layer 7 does not significantly negatively impact the display brightness of the electronic paper 100.

[0047] Reference Figure 9 and Figure 10 In some embodiments, the mesh 71 is shaped as one or more of the following: circular, square, hexagonal, or elliptical.

[0048] The mesh 71 disposed on the third electrode layer 7 can have various shapes. The shape of the mesh 71 can be selected according to actual process conditions and display requirements. Circular mesh 71 is relatively easy to process and has less stress concentration; square mesh 71 has certain advantages in space utilization, enabling a more compact arrangement of electrode materials on a plane; hexagonal mesh 71 has higher filling efficiency, providing more electrode borders while ensuring sufficient aperture ratio; elliptical mesh 71 can provide different opening sizes in different directions to adapt to specific optical design requirements. In the same third electrode layer 7, the shape of the mesh 71 can adopt one of the above shapes, or a combination of multiple shapes can be used according to different areas of the pixel unit. Regardless of the shape used, the core function of the mesh 71 is to provide a light transmission channel while retaining sufficient electrode material to form an effective third electrode layer 7.

[0049] Reference Figure 11 , Figure 11 This is a schematic flowchart of a method for manufacturing electronic paper according to an embodiment of the present invention. Applied to the manufacture of electronic paper 100 as described in at least some of the aforementioned embodiments, the method for preparing electronic paper 100 includes the following steps: S100: Place the cholesterol liquid crystal in a hot bath at a preset temperature; The preset temperature is usually between 80°C and 100°C. This temperature range keeps the cholesterol liquid crystal in an isotropic state, reduces its viscosity, and facilitates uniform mixing with other materials in the future.

[0050] Step S200: Add black charged particles 6 and photoluminescent material 4 into the cholesterol liquid crystal and mix them evenly.

[0051] Please refer to the reference. Figure 12 After preheating the cholesterol liquid crystal to an isotropic state, black charged particles 6 and photoluminescent material 4 are added and mixed to ensure thorough dispersion and uniform distribution of the components. It should be noted that... Figure 13 and Figure 14 The liquid crystal molecules in liquid crystal layer 1 shown can be in an isotropic disordered state. During the mixing process, low-shear stirring combined with ultrasonic-assisted dispersion can be used—magnetic stirring at 200 to 500 rpm for 15 to 30 minutes, supplemented by probe ultrasonication or water bath ultrasonication at a frequency of 20 kHz, with 30-second intervals between 30-second ultrasonications, or water bath ultrasonication, for a total time of 10 to 20 minutes, to prevent overheating and ensure uniform dispersion. Then, degassing and stabilization treatment is performed, specifically vacuum degassing at -0.1 MPa for 5 to 10 minutes to remove air bubbles introduced during mixing. Then, a small amount of polymer monomers (such as acrylates, 0.5 to 2 wt%) are added and prepolymerized using low-intensity ultraviolet light to form a sparse polymer network, physically hindering particle sedimentation or aggregation. Finally, it is naturally cooled to room temperature and then packaged for storage.

[0052] Step S300: Provide a first substrate assembly 2, on which a barrier 10 is provided to define a plurality of pixel spaces 11.

[0053] Please refer to the reference. Figure 12 The first substrate assembly 2 has a barrier wall 10 structure, which encloses and forms multiple independent pixel spaces 11, each pixel space 11 corresponding to a sub-pixel 5 region. The barrier wall 10 can be fabricated using photolithography, forming an isolation structure with a certain height through steps such as coating photoresist material, exposure, development, and curing.

[0054] Step S400: The uniformly mixed solution is added to the corresponding pixel space 11 according to the type of photoluminescent material 4.

[0055] Please refer to the reference. Figure 13A mixed solution containing cholesteric liquid crystal, photoluminescent material 4, and black charged particles 6 is added to the corresponding pixel space 11 according to the type of photoluminescent material 4—the mixed solution of red photoluminescent material 4 is added to the pixel space 11 of red sub-pixels 5, the mixed solution of green photoluminescent material 4 is added to the pixel space 11 of green sub-pixels 5, and the mixed solution of blue photoluminescent material 4 is added to the pixel space 11 of blue sub-pixels 5. The addition can be achieved using inkjet printing technology to precisely control the filling amount within each pixel space 11.

[0056] Step S500: Package the second substrate assembly 3. Align and bond the color filter substrate 31 with the second electrode layer 32 to the first substrate assembly 2 to complete the preparation of the electronic paper 100.

[0057] Please refer to the reference. Figure 14 The encapsulation process is carried out in a vacuum environment. The color filter substrate 31 and the array substrate 21 are bonded together with frame adhesive, and then subjected to photocuring and thermocuring treatments to firmly bond the two substrates together.

[0058] In the above embodiments of the present invention, after heating the cholesterol liquid crystal to an isotropic state, it is mixed and dispersed with photoluminescent material 4 and black charged particles 6, so that each functional component forms a uniform and stable blend system in the liquid crystal layer 1. This ensures the uniform absorption and conversion efficiency of the photoluminescent material 4 to transmitted light and the consistency of the electric field response of the black particles. Independent pixel spaces 11 are defined by the barrier wall 10 structure, and inkjet printing is used to fill the corresponding color sub-pixel 5 regions according to the type of photoluminescent material 4, achieving precise separation of the liquid crystal mixture solution between different color sub-pixels 5 and avoiding cross-contamination. By simultaneously introducing the photoluminescent material 4 and black charged particles 6 into the cholesterol liquid crystal and using the above preparation process, while improving light utilization and enhancing color purity, it also achieves control over dark-state display. Furthermore, the entire preparation process has good compatibility with existing mass production processes, is simple in process, low in cost, and suitable for large-scale production applications.

[0059] Reference Figure 15 , Figure 15 This is another schematic flowchart of a method for manufacturing electronic paper according to an embodiment of the present invention, applied to the manufacture of electronic paper 100 of at least some of the aforementioned embodiments. The method for preparing electronic paper 100 includes the following steps: Step S110: A first electrode layer 22 and a first photoresist layer 200 are sequentially disposed on the array substrate 21, and the first photoresist layer 200 is exposed; an intermediate electrode layer 400 and a second photoresist layer 300 are sequentially disposed on the first photoresist layer 200.

[0060] Please refer to the reference. Figure 16The array substrate 21 can be a thin-film transistor array substrate 21, and the first electrode layer 22 can be formed on the surface of the array substrate 21 by thin-film deposition. The first photoresist layer 200 is coated on the first electrode layer 22. After vacuum drying and pre-baking for shaping, the first photoresist layer 200 is exposed using a photomask 500 to form a latent image in the photoresist layer corresponding to the position of the barrier 10. The intermediate electrode layer 400 is formed on the first photoresist layer 200 by thin-film deposition, and the second photoresist layer 300 is coated on the intermediate electrode layer 400.

[0061] Please refer to the reference. Figure 17 Step S210: Expose and develop the second photoresist layer 300 to etch multiple mesh holes 71 on the intermediate electrode layer 400 to form the third electrode layer 7, and remove the second photoresist layer 300.

[0062] The second photoresist layer 300 is exposed and developed. Using the second photoresist layer 300 as a mask, the third electrode layer 7 is etched to form multiple mesh holes 71, thus forming the third electrode layer 7 of the mesh plate. After etching, the second photoresist layer 300 is removed.

[0063] Step S310: A third photoresist layer is disposed on the third electrode layer 7, and the third photoresist layer is exposed; wherein, the first photoresist layer 200 and the third photoresist layer are exposed using the same photomask 500.

[0064] A third photoresist layer is coated on the third electrode layer 7. After vacuum drying and pre-baking, the third photoresist layer is exposed using the same photomask 500 as in step S100. Therefore, the latent image positions formed in the first photoresist layer 200 and the third photoresist layer correspond to each other.

[0065] Step S410: Develop the first photoresist layer 200 and the third photoresist layer, leaving multiple spaced barrier walls 10, which define multiple pixel spaces 11.

[0066] Please refer to the reference. Figure 18 The first photoresist layer 200 and the third photoresist layer are developed, leaving multiple spaced-apart barrier walls 10. The barrier walls 10 are formed by the portions retained in the first photoresist layer 200 and the third photoresist layer, and the third electrode layer 7 is sandwiched at the middle height position of the barrier walls 10. Together, these barrier walls 10 and the third electrode layer 7 enclose and define multiple independent pixel spaces 11.

[0067] Step S510: Add a liquid crystal mixing solution to each pixel space 11. The liquid crystal mixing solution includes cholesteric liquid crystal and photoluminescent material 4 and black charged particles 6 dispersed in the cholesteric liquid crystal.

[0068] Please refer to the reference. Figure 19The liquid crystal mixture solution may also contain black charged particles 6 and photoluminescent material 4, and the preparation method is the same as in the previous embodiment. Cholesterol liquid crystal is placed in a hot bath at a preset temperature; the preset temperature is typically 80°C to 100°C. This temperature range keeps the cholesterol liquid crystal in an isotropic state, reducing its viscosity and facilitating subsequent uniform mixing with other materials. Then, black charged particles 6 and photoluminescent material 4 are added to the cholesterol liquid crystal and mixed uniformly. Specifically, inkjet printing technology can be used, adding the photoluminescent material 4 to the corresponding pixel space 11 according to its type. At this point, both the black charged particles 6 and the photoluminescent material 4 are uniformly dispersed within the liquid crystal. The black charged particles 6 will aggregate or move under the influence of an electric field. The photoluminescent material 4 itself is uncharged and will not move under the influence of an electric field. After the liquid crystal cools, it is uniformly dispersed in the liquid crystal layer 1.

[0069] Step S610: Package the second substrate assembly 3.

[0070] Please refer to the reference. Figure 19 The second substrate assembly 3 includes a color filter substrate 31 and a second electrode layer 32 disposed on the color filter substrate 31. The color filter substrate 31 and the array substrate 21 are aligned, bonded, and encapsulated to complete the fabrication of the electronic paper 100. The encapsulation process is carried out in a vacuum environment. The color filter substrate 31 and the array substrate 21 are bonded together with frame adhesive, and then subjected to photocuring and thermocuring treatments. The electronic paper 100 prepared by the above method has a third electrode layer 7 with a grid plate in the middle of its liquid crystal layer 1, which can effectively shorten the migration distance of black charged particles 6 and improve the response speed. At the same time, the barrier wall 10 structure ensures the independence between each pixel unit and avoids cross-contamination between different color sub-pixels 5.

[0071] In the above embodiments of the present invention, a third electrode layer 7 is formed by etching multiple mesh holes 71 on the intermediate electrode layer 400. This allows the third electrode layer 7 to function as an intermediate electrode for electric field regulation while ensuring that light can pass through the mesh hole 71 area and propagate normally in the liquid crystal layer 1 without significantly negatively impacting display brightness. By using the same photomask 500 to expose the first photoresist layer 200 and the third photoresist layer, the positions of the barrier wall 10 patterns formed in the upper and lower photoresist layers are precisely aligned, ensuring the alignment accuracy of the barrier wall 10 structure and the size consistency of the pixel space 11. This avoids problems such as pixel space 11 deformation or exposure of the third electrode layer 7 caused by misalignment of the upper and lower barrier walls 10. By sandwiching the third electrode layer 7 at the middle height of the barrier wall 10, the distance that black charged particles 6 need to migrate from one side electrode to the middle electrode is shortened to half its original distance, significantly improving the migration rate and response speed of black particles. By defining independent pixel spaces 11 through the barrier wall 10 structure and adding liquid crystal mixing solution using inkjet printing, effective isolation between different color sub-pixels 5 is achieved. The entire preparation process is highly compatible with the existing array substrate 21 manufacturing process. The process steps are clear and highly controllable, making it suitable for mass production.

[0072] According to some embodiments of this application, this application provides a display device, which includes the electronic paper 100 of any of the above.

[0073] The display device can be an e-reader, electronic tag, smart card, billboard, mobile terminal, or any other device that uses electronic paper 100 as a display element. Because the electronic paper 100 possesses the structural features described in the foregoing embodiments—including a liquid crystal layer 1 with dispersed photoluminescent material 4, black charged particles 6, and an optional third electrode layer 7—this display device can reuse the transmitted portion of the incident light during display, effectively improving light utilization and display brightness. Simultaneously, the electric field control of the black charged particles 6 achieves pure dark-state display and good contrast, resulting in excellent display effects and user experience. Since the display device includes all the technical solutions of any of the above embodiments, it possesses at least all the beneficial effects brought by the above technical solutions, which will not be elaborated upon here.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the patent scope of this invention. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that, under the technical concept of this invention, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; or they can be directly / indirectly applied to other related technical fields. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electronic paper, characterized in that, The device includes a first substrate assembly and a second substrate assembly disposed opposite to each other, with a plurality of pixel units disposed between the first substrate assembly and the second substrate assembly, each pixel unit having a liquid crystal layer disposed therein, and each liquid crystal layer having a photoluminescent material disposed therein.

2. The electronic paper according to claim 1, characterized in that, The photoluminescent material is dispersed within the liquid crystal layer.

3. The electronic paper according to claim 1, characterized in that, The plurality of pixel units include a variety of sub-pixels. The number of types of photoluminescent materials is set to correspond to the number of types of sub-pixels. Part of the incident light is reflected on the surface of the liquid crystal layer, and the photoluminescent material can be excited by another part of the light transmitted into the liquid crystal layer, thereby emitting light corresponding to the sub-pixel.

4. The electronic paper according to claim 1, characterized in that, In each pixel unit, the mass fraction of the liquid crystal layer is 85% to 95%, the mass fraction of the photoluminescent material is 0.5% to 10%, and the photoluminescent material is uniformly distributed in the liquid crystal layer.

5. The electronic paper according to claim 1, characterized in that, The liquid crystal layer contains black charged particles that can move under the influence of the electric fields of the first substrate assembly and the second substrate assembly to control the display brightness of the corresponding pixel unit.

6. The electronic paper according to claim 5, characterized in that, The first substrate assembly includes an array substrate and a first electrode layer; the second substrate assembly includes a color filter substrate and a second electrode layer, with the first electrode layer and the second electrode layer disposed opposite to each other; the electronic paper further includes a third electrode layer disposed between the first electrode layer and the second electrode layer, the third electrode layer and the first electrode layer forming a first electric field region, and the third electrode layer and the second electrode layer forming a second electric field region.

7. The electronic paper according to claim 6, characterized in that, The third electrode layer includes a mesh plate with multiple mesh holes.

8. A method for preparing electronic paper, characterized in that, The method for preparing the electronic paper includes the following steps: Place the cholesterol liquid crystal in a hot bath at a preset temperature; Black charged particles and photoluminescent material are added to the cholesterol liquid crystal and mixed evenly. A first substrate assembly is provided, and a barrier is provided on the first substrate assembly to define a plurality of pixel spaces; The well-mixed solution is added to the corresponding pixel space according to the type of photoluminescent material; Encapsulate the second substrate assembly.

9. A method for preparing electronic paper, characterized in that, The method for preparing the electronic paper includes the following steps: A first electrode layer and a first photoresist layer are sequentially disposed on an array substrate, and the first photoresist layer is exposed; an intermediate electrode layer and a second photoresist layer are sequentially disposed on the first photoresist layer. The second photoresist layer is exposed and developed to etch multiple mesh holes on the intermediate electrode layer to form the third electrode layer, and the second photoresist layer is removed. A third photoresist layer is disposed on the third electrode layer, and the third photoresist layer is exposed; wherein, the first photoresist layer and the third photoresist layer are exposed using the same photomask; The first photoresist layer and the third photoresist layer are developed to leave multiple spaced baffles, which define multiple pixel spaces. A liquid crystal mixing solution is added to each pixel space; the liquid crystal mixing solution includes cholesterol liquid crystal and photoluminescent material and black charged particles dispersed in the cholesterol liquid crystal; Encapsulate the second substrate assembly.

10. A display device, characterized in that, The display device includes electronic paper according to any one of claims 1-7.

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