Ultra-high-resolution display pixel black matrix based on maskless gray exposure technology and preparation method of ultra-high-resolution display pixel black matrix

Abstract

The invention provides an ultrahigh-resolution display pixel black matrix based on a maskless gray exposure technology and a preparation method of the ultrahigh-resolution display pixel black matrix. And processing a black matrix structure with a stepped or gradient section through gray exposure. The stepped black matrix structure enables the quantum dot material to inhibit evaporation of an edge area after ink-jet printing, and controls an evaporation path and a flowing direction of a solvent. The Malangei effect caused in the evaporation process effectively promotes migration of the solvent and the particles to the middle area, and particle outward migration caused by capillary flow is inhibited. In addition, most of the quantum dots on the periphery are brought to be gathered towards the middle area in the solvent evaporation process of the middle area, the quantum dots in the middle area emit light with the specific wavelength after being excited, and the luminous intensity and optical performance of the color conversion layer are further improved. The method is suitable for manufacturing high-performance ultrahigh-resolution display color conversion layers, photoelectric devices and other optical assemblies, and an innovative scheme is provided for light regulation and control and improvement of luminous efficiency.

Description

Technical Field

[0001] The present invention relates to the field of display technology and micro-nano structure manufacturing technology, in particular to an ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology and a preparation method thereof. Background Art

[0002] Black matrix is ​​a key structure used in displays, mainly used to absorb stray light, improve contrast, and provide partition support for luminescent materials. Traditional black matrices are usually made of opaque materials (such as metal or black photoresist) and are formed on the surface of displays or other optical devices through processes such as photolithography and etching. These black matrices can effectively prevent light from crosstalking between pixels, thereby improving display performance.

[0003] In recent years, with the development of new luminescent materials such as quantum dots and OLEDs, displays have put forward higher requirements on the structure of the black matrix, requiring it to maintain good light absorption performance and have precise micro-nano structures to improve light extraction efficiency and luminescence uniformity. In addition, inkjet printing of quantum dots, as an important method for depositing luminescent materials, has attracted widespread attention due to its flexible pattern control and material saving advantages. However, the coffee ring effect (i.e., the solvent gathers at the edge, causing the material to be sparse in the center) is prone to occur during inkjet printing, which seriously affects the uniformity and performance of the luminescent layer.

[0004] At present, the solutions to the coffee ring effect are mostly focused on optimizing solvent formulations or printing parameters, but these methods have limited effects and cannot fundamentally solve the problem of quantum dots flowing to the edge during the deposition process. Therefore, developing a black matrix with a special structure that can inhibit the edge aggregation of materials during solvent evaporation and further improve the light extraction efficiency of luminescent materials has become an important research direction in the field of display devices. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide an ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology and a preparation method thereof, wherein a black matrix with a stepped structure is processed by grayscale photolithography technology, and an opening is provided in the middle part of the structure, and only the solvent is allowed to evaporate in the middle part, thereby effectively suppressing the coffee ring effect. At the same time, quantum dots gather toward the center of the black matrix driven by solvent evaporation, so that the luminescent material is more concentrated in the luminescent area.

[0006] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology, comprising a substrate and a black matrix; a plurality of grooves are extended downward on a side of the black matrix facing away from the substrate, and the grooves are arranged in an array; the cross-section of the groove in a direction perpendicular to the plane where the black matrix is ​​located is an axially symmetrical shape; along the depth direction of the groove, the opening of the groove is wide at the bottom and narrow at the top, and the groove is filled with a luminescent material.

[0007] In a preferred embodiment, one side of the axisymmetric shape is specifically a step, an arc or a line segment.

[0008] In a preferred embodiment, the layer height H of the groove is determined based on the LED thickness T, the incident angle, i.e., the inclination angle θ of the LED light, and the refractive index n of the black matrix material to ensure uniform extraction and guidance of light:

[0009]

[0010] p is a control factor used to adjust the light extraction intensity and is set between 0.5 and 1.5;

[0011] The step opening diameter D is determined by the backlight pixel unit diameter d and the offset distance L of the Marangoni flow, and the formula is as follows:

[0012]

[0013] c is the correction coefficient, which is in the range of 0.1-0.5.

[0014] In a preferred embodiment, the upper opening area of ​​the black matrix is ​​circular, elliptical, rectangular, hexagonal or other polygonal shapes, and the lower opening area of ​​the black matrix is ​​circular, elliptical, rectangular, hexagonal or other polygonal shapes.

[0015] In a preferred embodiment, display screens suitable for the black matrix structure include liquid crystal display screens LCD, organic light emitting diode (OLED) display screens, and micro light emitting diode (Micro-LED) display screens.

[0016] The present invention also provides a method for preparing an ultra-high resolution display pixel black matrix based on a maskless grayscale exposure technology, and prepares the above-mentioned ultra-high resolution display pixel black matrix based on a maskless grayscale exposure technology; the method comprises the following steps:

[0017] Step 1: Select a transparent or semi-transparent substrate suitable for the black matrix;

[0018] Step 2: Evenly coat the black photoresist on the surface of the substrate, and control the thickness of the photoresist to be within the range of 0.5 μm–15 μm;

[0019] Step 3: Expose the photoresist layer; adjust the light intensity to 10mJ / cm 2 –500mJ / cm 2 The grayscale exposure time is between 0.05 seconds and 15 seconds to form different levels of height of the required black matrix cross-sectional structure with a wide bottom and a narrow top. The exposure process uses the linear or nonlinear relationship between the step-by-step grayscale change and the photoresist layer height to control the height of each level within the range of 0.05μm-5μm.

[0020] Step 4: Developing the exposed substrate; removing unexposed or partially exposed areas by adjusting the developing time between 10 seconds and 300 seconds and the developer concentration between 0.1% and 5%, thereby forming a black matrix with a multi-step or gradient cross-section structure;

[0021] Step 5: The developed substrate is subjected to baking or annealing heat treatment at a temperature ranging from 60°C to 250°C;

[0022] Step 6: Fill the luminescent material into the black matrix structure;

[0023] Step 7: Drying or oven drying at a temperature range of 30°C–180°C;

[0024] Step 8: Attach the prepared black matrix to the display screen or other optoelectronic component surface and perform packaging processing.

[0025] In a preferred embodiment, in step 1, the substrate used to prepare the black matrix includes a glass substrate, an ITO conductive substrate, or an inorganic thin film substrate with high light transmittance.

[0026] In a preferred embodiment, in step 2, the black photoresist is uniformly coated on the surface of the substrate by spin coating, screen printing or slit coating.

[0027] In a preferred embodiment, in step 3, the black matrix forming method includes maskless grayscale exposure, laser direct writing and nano-imprinting.

[0028] In a preferred embodiment, in step 6, the luminescent material includes quantum dot material, organic luminescent material, inorganic phosphor, rare earth doped nanoparticles or dye molecules.

[0029] Compared with the prior art, the present invention has the following beneficial effects: a step-shaped or gradient cross-sectional structure is formed on a black photoresist by using a maskless grayscale exposure technique, and each step or gradient structure of the structure can achieve different level heights by adjusting the exposure grayscale to optimize light extraction efficiency, illumination uniformity and irradiance performance. The opening area of ​​the step structure of the black matrix is ​​wide at the bottom and narrow at the top, allowing the solvent in the middle area to evaporate preferentially from the opening area, and the solvent in the edge area is inhibited from evaporating due to the restriction of the black matrix steps, while the edge aggregation of the quantum dot material is also inhibited. The Marangoni effect induced during the evaporation process effectively promotes the migration of solvents and particles to the middle area, inhibits the outward migration of particles caused by capillary flow, and thus effectively inhibits the generation of the coffee ring effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of a black matrix processed by grayscale photolithography according to a preferred embodiment of the present invention;

[0031] Figure 2 A schematic diagram of the application of a color conversion layer according to a preferred embodiment of the present invention;

[0032] Figure 3 A schematic diagram of solvent evaporation in a preferred embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of a single pixel of a color conversion layer in which quantum dots converge toward the middle after solvent evaporation according to a preferred embodiment of the present invention;

[0034] Figure 5 A schematic diagram of a single pixel of a quantum dot color conversion layer prepared by exposure attenuation according to a preferred embodiment of the present invention;

[0035] Figure 6 This is a schematic diagram of processing black matrices of other shapes according to a preferred embodiment of the present invention;

[0036] Figure 7 This is a schematic diagram of a single pixel of a curved quantum dot color conversion layer inside a black matrix in a preferred embodiment of the present invention;

[0037] Figure 8 This is a schematic diagram of a single pixel of a quantum dot color conversion layer with an inner side tilted on a black matrix in a preferred embodiment of the present invention;

[0038] Fig. 9 A schematic diagram of inkjet printing according to a preferred embodiment of the present invention;

[0039] Fig.10 A schematic diagram of a black matrix processed by two-grayscale photolithography according to a preferred embodiment of the present invention;

[0040] Fig.11 This is a schematic diagram of the structure of the third preferred embodiment of the present invention being applied to a flexible material;

[0041] Fig.12 The structure distribution diagram and simulation schematic diagram of the structure of the preferred embodiment of the present invention in the LightTools software, wherein: (a) is the structure distribution diagram of the structure, and (b) is the simulation schematic diagram;

[0042] Fig.13 Schematic diagram of the workflow of the first, second and third color conversion layers in the preferred embodiment of the present invention.

[0043] Description of the accompanying drawings:

[0044] Figure 1 :100: grayscale photolithography lens, 200: ultraviolet light, 300: black matrix, 500: excitation light source, 3001: three-dimensional black matrix cross section

[0045] Figure 2 :300:Black matrix,400:Quantum dots or other luminescent materials,500:Excitation light source,700:Inkjet print head

[0046] Figure 3 :3002:Two-dimensional black matrix cross section, 400:Quantum dots or other luminescent materials

[0047] Figure 4 :3002:2D black matrix cross section,400:quantum dots or other luminescent materials,500:excitation light source,600:tracing light

[0048] Figure 5 :3002:Two-dimensional black matrix cross section, 400:Quantum dots or other luminescent materials

[0049] Figure 6 :100: grayscale photolithography lens, 200: ultraviolet light, 300: black matrix, 500: excitation light source,

[0050] Figure 7 :3002:2D black matrix cross section,400:quantum dots or other luminescent materials,500:excitation light source,600:tracing light

[0051] Figure 8 :3002:2D black matrix cross section,400:quantum dots or other luminescent materials,500:excitation light source,600:tracing light

[0052] Fig. 9 :300:Black matrix,400:Quantum dots or other luminescent materials,700:Inkjet print head,800:Glass substrate,900:Base

[0053] Fig.10:100: grayscale photolithography lens, 200: ultraviolet light, 300: black matrix, 800: glass substrate, 900: base

[0054] Fig.11 :300:Black matrix,700:Inkjet print head,400:Quantum dots or other luminescent materials,1100:Blue LED

[0055] Fig.12 (a): 300: black matrix, 400: quantum dots or other luminescent materials, 1100: blue LED, 1101: LED mask

[0056] Fig.12 (b): 300: black matrix, 600: ray tracing, 1101: LED mask. DETAILED DESCRIPTION

[0057] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0058] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0059] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0060] An ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology, reference Figure 1-12 , comprising a substrate and a black matrix; a plurality of grooves are extended downward on a side of the black matrix facing away from the substrate, and the grooves are arranged in an array; the cross section of the groove in a direction perpendicular to the plane where the black matrix is ​​located is an axisymmetric shape; along the depth direction of the groove, the opening of the groove is wide at the bottom and narrow at the top, and the groove is filled with a luminescent material. One side of the axisymmetric shape is specifically a step, an arc or a line segment.

[0061] A hollow structure is formed in the black matrix, which can accommodate and fill color conversion materials such as quantum dots or other scattering materials containing solvents. The solvent evaporation process produces a Marangoni effect due to the limitation of the gradient structure of the black matrix, so that most of the surrounding quantum dots and other particle materials gather in the central area, thereby improving the luminous intensity and luminous efficiency of the color conversion layer.

[0062] After filling, the quantum dot material naturally gathers in the middle area through solvent evaporation, achieving uniform deposition and high-quality pattern formation. The aggregation process is based on the Marangoni effect and the principle of capillary flow suppression: during the solvent evaporation process, the Marangoni effect caused by the change in surface tension gradient causes the solvent and particles to flow from the low surface tension area to the high surface tension area, driving the quantum dot material to concentrate in the middle area of ​​the black matrix opening; at the same time, the black matrix step structure design suppresses the outward migration of particles caused by capillary flow, thereby effectively suppressing the generation of the coffee ring effect. The black matrix structure can be excited by the short-wavelength pixel array of blue light / ultraviolet light or the whole light source of the backlight to achieve full-color light emission with high color saturation, which is suitable for the preparation of color conversion layers of high-performance ultra-high resolution displays, the manufacture of optoelectronic devices and other optical components.

[0063] In order to meet the black matrix structure of different sizes and optical requirements, the following fitting formula can be used to accurately optimize the height of each step and the aperture. The formula takes into account the proportional relationship of the LED chip size, the light path simulation requirements, and the requirements for reducing the coffee ring effect.

[0064] (1) Step height formula

[0065] The step height H can be determined based on the LED thickness T, the angle of incidence (the inclination of the LED light) θ, and the material refractive index n to ensure uniform extraction and guidance of the light:

[0066]

[0067] in:

[0068] H represents the height of each step;

[0069] T represents the thickness of the LED chip;

[0070] n is the refractive index of the black matrix material (usually about 1.6-2.0, varying slightly depending on the material);

[0071] θ is the angle of incident light (depending on the design of the light source, the recommended range is 0-30°);

[0072] p is a control factor used to adjust the light extraction intensity and is usually set between 0.5 and 1.5.

[0073] For example, for an LED with a thickness of 50 μm, a refractive index of 1.7, and an incident angle of 20°, if (p = 1), then:

[0074]

[0075] By adjusting the refractive index n and the incident angle θ, more light source types can be accommodated.

[0076] (2) Step opening diameter formula

[0077] The step opening diameter (D) can be determined by the LED chip diameter (d) and the offset distance (L) of the Marangoni flow to help suppress the coffee ring effect. The formula is as follows:

[0078]

[0079] in:

[0080] D represents the opening diameter of each step;

[0081] d represents the diameter of the LED chip;

[0082] L is the offset distance caused by the Marangoni effect, usually between 5 and 20 μm;

[0083] c is the correction factor, which is usually set in the range of 0.1-0.5 to adapt to different solvent flow characteristics.

[0084] Assuming the LED chip diameter is 100 μm, the LED thickness is 50 μm, the offset distance is (L = 10, mu m), and (c = 0.3),

[0085] but:

[0086]

[0087] (3) Adjustment of additional parameters

[0088] Furthermore, for flexibility and wider coverage, different incident angles and offset distances can be selected to tune the optical performance and fluid control properties to obtain efficient light extraction and anti-coffee ring structures.

[0089] The height and shape of the step structure of the black matrix can be limited according to the manufacturing process to achieve optimized light extraction efficiency and illumination uniformity. The cross-sectional shape of the step structure is not limited to right-angle steps, but may also include rounded corners, beveled corners, tapers or other non-right-angle designs to further improve the light management effect and uniform deposition performance of quantum dot materials.

[0090] At the same time, since the exposure amount naturally decays as the thickness of the black matrix increases during the maskless grayscale exposure process, the resulting step cross-section may form a non-ideal right angle. This gradually changing shape still falls within the scope of protection of the present invention.

[0091] The upper and lower opening areas of the black matrix can be circular, elliptical, rectangular, hexagonal or other polygonal shapes, and the upper and lower openings can be of different shapes to adapt to different optical designs and display application requirements, and to optimize light extraction efficiency, illumination uniformity and luminous intensity.

[0092] Display screens suitable for the black matrix structure include liquid crystal display screens (LCD), organic light-emitting diode (OLED) display screens, and micro-light-emitting diode (Micro-LED) display screens, etc., whose display pixels match the black matrix opening area to ensure that each pixel is aligned with the corresponding black matrix opening to improve display contrast, reduce light leakage, and optimize color saturation and brightness uniformity. The narrow outlet end or the wide outlet end forms a close coupling with the pixel to confine the pixel light emission to the black matrix as much as possible. In another embodiment, the black matrix structure can adopt another design, that is, the upper opening is larger and the lower opening is smaller. This design provides the following advantages: First, the larger upper opening can directly enhance the light extraction efficiency, allowing more light to be emitted from the quantum dot material area, reducing the reflection loss of the side wall; secondly, the structure of wide top and narrow bottom optimizes the optical path, making it easier for the light emission at the bottom to propagate to the display surface, and improving the concentration and directionality of the light beam; in addition, the larger upper opening facilitates the uniform evaporation of the solvent, reduces the accumulation of quantum dots at the edge, and theoretically can also suppress the coffee ring effect to a certain extent, thereby improving the uniformity of the pattern; finally, the side wall can also achieve light reflection and guidance through coating, making the emitted light more directional.

[0093] The quantum dot material is filled into the black matrix structure layer by layer through a combination of methods including but not limited to multiple inkjet printing, spin coating or other filling processes. If the quantum dot material cannot completely fill the opening area, a second or multiple fillings may be performed, or transparent polymers, photocurable resins or other inorganic materials may be used to fill the remaining space to ensure the flatness of the black matrix surface and improve the display quality.

[0094] Through processes including but not limited to vacuum evaporation, magnetron sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), etc., a film is coated on the inner sidewall steps of the black matrix to increase light reflectivity or reduce light absorption and improve energy utilization efficiency. The coating material includes but is not limited to metal oxides, dielectric layers or multilayer interference films to further improve light extraction efficiency and quantum dot luminescence intensity.

[0095] The preparation process includes but is not limited to the following steps:

[0096] (1) Substrate preparation

[0097] Select a transparent or semi-transparent substrate suitable for the black matrix, including but not limited to a glass substrate, an ITO conductive substrate, or an inorganic thin film substrate with high light transmittance. Use methods such as ultrasonic cleaning, plasma cleaning, etc. to clean and dry the substrate to ensure a clean surface.

[0098] (2) Black photoresist coating

[0099] The black photoresist is evenly coated on the surface of the substrate by methods including but not limited to spin coating, screen printing, slit coating, etc., and the thickness of the photoresist is controlled within the range of 0.5-15μm to meet the design requirements of the target black matrix step structure.

[0100] (3) Maskless grayscale exposure

[0101] The photoresist layer is exposed using maskless grayscale exposure technology. By adjusting the light intensity between 10–500 mJ / cm 2 The exposure time is between 0.05 and 15 seconds to form the required black matrix step or gradient cross-sectional structure with different levels of height. The exposure process uses the linear or nonlinear relationship between the step-by-step grayscale change and the height of the photoresist layer so that the height of each level can be controlled within the range of 0.05-5μm. The black matrix forming method includes but is not limited to maskless grayscale exposure, laser direct writing and nanoimprinting, so as to obtain black matrix structures with different levels of height, thereby optimizing light extraction efficiency and optical performance.

[0102] (4) Development

[0103] The exposed substrate is subjected to development treatment, and the development methods include but are not limited to spray development and immersion development. The unexposed or partially exposed areas are removed by adjusting the development time between 10-300 seconds and the developer concentration between 0.1-5%, forming a black matrix with a multi-step or gradient cross-section structure to ensure the clarity and consistency of the structure.

[0104] (5) Heat treatment

[0105] The developed substrate is baked or annealed by methods including but not limited to hot plate baking and annealing, with the temperature ranging from 60-250°C to further stabilize the structure of the black photoresist and ensure the long-term stability and mechanical strength of the black matrix.

[0106] (6) Filling materials

[0107] The black matrix structure is filled with luminescent materials, including but not limited to quantum dot materials, organic luminescent materials, inorganic phosphors, rare earth doped nanoparticles and dye molecules. The filling methods include but are not limited to inkjet printing, spin coating, screen printing and drop coating. For inkjet printing, the inkjet printing of quantum dot materials is performed above the opening area of ​​the black matrix, and the inkjet parameters such as drop volume, printing speed and inkjet spacing are controlled to ensure uniform distribution of the solvent, optimize solvent flow and suppress the coffee ring effect.

[0108] (7) Drying or baking

[0109] Drying or baking treatment is performed in the temperature range of 30–180°C to accelerate the evaporation of the solvent, ensure that the filling material is uniformly deposited and solidified in the black matrix structure, and improve the luminescence performance of the structure.

[0110] (8) Packaging and bonding

[0111] The prepared black matrix is ​​adhered to the display screen or other optoelectronic component surface and encapsulated to enhance the durability and environmental stability of the black matrix structure, ensuring high-resolution luminous effects and improved optical performance in display applications.

[0112] In LightTools, the length, width, and height of the geometry are set to 200μm, 200μm, and 100μm, respectively, that is, a Mini-LED chip with a size of 200×200μm (refer to the Mini-LED commercial standard). Disable surface emission on the front, back, left, right, and bottom surfaces of the geometry, making the top surface the only luminous surface. Set the luminous angle distribution of the top surface to "Lambertian distribution", the spatial distribution to "uniform", and the tracing direction to "outward". The Mini-LED lamp bead luminescence model generated in this way has the center of its luminous surface located at the origin of the XYZ coordinate system. The blue light spectrum data of the corresponding Mini-LED is then imported as the excitation light source spectrum. Based on the PMMA matrix, particles with volume scattering effects are added to the PMMA material, and by adjusting the parameters of these particles, the absorption spectrum, emission spectrum, concentration, and quantum yield of quantum dots of different colors are simulated to simulate the behavior of quantum dots or other luminescent materials. The black matrix material was set to full absorption, and an LED mask was set to absorb the leaked blue light to prevent it from affecting the simulation results. 5,000,000 light rays were traced, and an infinite field receiver was set to observe the effect of the above structure on the performance of the color conversion layer.

[0113] Embodiment 1

[0114] like Fig. 9 As shown, this embodiment provides a method for improving color conversion performance by using a special black matrix in inkjet printing. In this embodiment, a black matrix structure 300 with stepped grooves is first processed on a glass substrate 800 on a base 900 using a grayscale photolithography lens. The shape of the groove is designed to be a stepped structure with a small opening at the top and a wider bottom. This design allows only the middle part to allow the solvent of the quantum dots or other light-emitting materials 400 to evaporate. The black matrix 300 is made of black photoresist to absorb excess light and improve display contrast.

[0115] Next, the red, green, and blue quantum dot materials or other luminescent materials 400 are sprayed into the corresponding black matrix grooves 300 through the inkjet print head 700. The solvent begins to evaporate from the middle opening of the groove. During the evaporation process, due to the action of capillary force, the surrounding quantum dots are gradually driven to gather in the central area. This design effectively suppresses the coffee ring effect common in inkjet printing, that is, the phenomenon that the solvent carries the material to the edge and causes uneven distribution of the material.

[0116] In addition, since the quantum dot material is concentrated in the middle area, the light extraction efficiency in this area is improved. Coupled with the light absorption characteristics of the black matrix itself, the interference of stray light can be significantly reduced, achieving higher color purity and light conversion efficiency.

[0117] This embodiment is suitable for the preparation of pixel light-emitting layers of quantum dot light-emitting diode (QLED) displays and micro LED displays, and can theoretically improve the brightness uniformity and color expression of the display.

[0118] The workflow of the optical structure is as follows Fig.13 As shown, the specific working status is as follows:

[0119] In the optical structure, the excitation light source 500 emits light of a specific wavelength, which can excite the luminescent material 400. A portion of the light emitted by the excitation light source 500 is absorbed by the black matrix 300, and a portion is scattered in the quantum dots or other luminescent materials 400 or excites the luminescent material or passes through the luminescent material (such as quantum dots). A portion of the scattered and transmitted light re-excites the luminescent material, a portion is directly emitted together with the light emitted by the luminescent material, and another portion is absorbed by the black matrix, and finally the color conversion is completed.

[0120] Embodiment 2

[0121] like Fig.10 As shown, this embodiment provides a method for preparing a black matrix by grayscale exposure. This embodiment shows the application of a black matrix structure 300 in a quantum dot color conversion layer. A black matrix 300 with a multi-layer stepped structure is processed on the surface of a glass substrate 800 using a grayscale photolithography lens 100. The number of steps and the height and width of each step layer are precisely controlled by design to achieve the best light extraction effect of light of different wavelengths.

[0122] In this structure, the bottom provides an excitation light source through a blue light micro-LED. When the blue light enters the groove, it excites the red and green light quantum dot materials or other luminescent materials respectively to complete the light conversion. Because the grooves of the black matrix are designed as a multi-layer stepped structure, light is refracted and reflected at different depths, maximizing light extraction efficiency and preventing light loss.

[0123] In addition, through blue light excitation, most of the quantum dot areas concentrated in the center of the groove participate in luminescence. This concentration of light further improves the luminous intensity and uniformity of the color conversion layer. In addition, the black matrix 300 can effectively absorb unconverted blue light and reduce stray light interference. This structure is suitable for the efficient preparation of quantum dot color conversion layers, which helps to achieve a wide color gamut and high color saturation display effect.

[0124] This embodiment is applicable to quantum dot backlight displays and HDR displays, and has significant advantages, especially in display devices with high brightness and high color reproduction.

[0125] The workflow of the optical structure is as follows Fig.13 As shown, the specific working status is as follows:

[0126] In the optical structure, the excitation light source 500 emits light of a specific wavelength, which can excite the luminescent material 400. A portion of the light emitted by the excitation light source 500 is absorbed by the black matrix 300, and a portion is scattered in the quantum dots or other luminescent materials 400 or excites the luminescent material or passes through the luminescent material (such as quantum dots). A portion of the scattered and transmitted light re-excites the luminescent material, a portion is directly emitted together with the light emitted by the luminescent material, and another portion is absorbed by the black matrix, and finally the color conversion is completed.

[0127] Embodiment 3

[0128] like Fig.11 As shown, this embodiment provides a method for applying the designed black matrix structure to the light-emitting layer of a flexible display. In this embodiment, the designed black matrix structure 300 is applied to the light-emitting layer of the flexible display. The black matrix material 300 uses a composite material of a conductive polymer and a black photoresist to ensure the adhesion and stability of the black matrix on the flexible substrate 1000.

[0129] A stepped groove 300 with a small opening is processed on the flexible substrate 1000 by a grayscale photolithography lens 100. Subsequently, quantum dots or other luminescent materials 400 are deposited in the groove 300 by an inkjet printing nozzle 700. After printing, due to the special design of the black matrix 300, only the middle part allows the solvent to evaporate, thereby preventing the solvent from driving the quantum dots to diffuse around. This design can also suppress the coffee ring effect, so that the quantum dot material is evenly distributed in the center of the groove, and the uniformity of the luminescent layer will not be affected even when the flexible substrate 1000 is bent or curled.

[0130] The flexible black matrix structure can also maintain its structural integrity and light absorption capability when the flexible substrate 1000 is deformed, and improve the brightness and luminous efficiency of the flexible display by concentrating the light-emitting area.

[0131] This embodiment is suitable for display devices that require high luminous efficiency and flexibility, such as wearable devices, foldable screen mobile phones, and flexible OLED displays.

[0132] The workflow of the optical structure is as follows Fig.13 As shown, the specific working status is as follows:

[0133] In the optical structure, the excitation light source 500 emits light of a specific wavelength, which can excite the luminescent material 400. A portion of the light emitted by the excitation light source 500 is absorbed by the black matrix 300, and a portion is scattered in the quantum dots or other luminescent materials 400 or excites the luminescent material or passes through the luminescent material (such as quantum dots). A portion of the scattered and transmitted light re-excites the luminescent material, a portion is directly emitted together with the light emitted by the luminescent material, and another portion is absorbed by the black matrix, and finally the color conversion is completed.

Claims

1. An ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology, characterized in that: It comprises a substrate and a black matrix; a plurality of grooves are extended downward from a side of the black matrix facing away from the substrate, and the grooves are arranged in an array; the cross section of the groove in a direction perpendicular to the plane where the black matrix is ​​located is an axially symmetrical shape; along the depth direction of the groove, the opening of the groove is wide at the bottom and narrow at the top, and the groove is filled with a luminescent material.

2. The ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology according to claim 1, characterized in that: One side of the axisymmetric shape is specifically a step, an arc or a line segment.

3. The ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology according to claim 1, characterized in that: The layer height H of the groove is determined based on the LED thickness T, the incident angle, i.e. the inclination angle θ of the LED light, and the refractive index n of the black matrix material to ensure uniform extraction and guidance of light: p is the control factor used to adjust the light extraction intensity and is set between 0.5 and 1.5; The step opening diameter D is determined by the backlight pixel unit diameter d and the offset distance L of the Marangoni flow, and the formula is as follows: c is the correction coefficient, which is in the range of 0.1-0.

5.

4. The ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology according to claim 1, characterized in that: The upper opening area of ​​the black matrix is ​​circular, elliptical, rectangular, hexagonal or other polygonal shapes, and the lower opening area of ​​the black matrix is ​​circular, elliptical, rectangular, hexagonal or other polygonal shapes.

5. The ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology according to claim 1, characterized in that: Display screens suitable for this black matrix structure include liquid crystal displays (LCD), organic light-emitting diode (OLED) displays, and micro-light-emitting diode (Micro-LED) displays.

6. A method for preparing an ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology, characterized in that: An ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology as described in any one of claims 1 to 5 is prepared; comprising the following steps: Step 1: Select a transparent or semi-transparent substrate suitable for the black matrix; Step 2: Evenly coat the black photoresist on the substrate surface, and control the thickness of the photoresist to be within the range of 0.5 μm–15 μm; Step 3: Expose the photoresist layer; adjust the light intensity to 10mJ / cm 2 –500mJ / cm 2 The grayscale exposure time is between 0.05 seconds and 15 seconds to form different levels of height of the required black matrix cross-sectional structure with a wide bottom and a narrow top. The exposure process uses the linear or nonlinear relationship between the step-by-step grayscale change and the photoresist layer height to control the height of each level within the range of 0.05μm-5μm. Step 4: Developing the exposed substrate; removing unexposed or partially exposed areas by adjusting the developing time between 10 seconds and 300 seconds and the developer concentration between 0.1% and 5%, thereby forming a black matrix with a multi-step or gradient cross-section structure; Step 5: The developed substrate is subjected to baking or annealing heat treatment at a temperature ranging from 60°C to 250°C; Step 6: Fill the luminescent material into the black matrix structure; Step 7: Drying or oven drying at a temperature range of 30°C–180°C; Step 8: Attach the prepared black matrix to the display screen or other optoelectronic component surface and perform packaging processing.

7. The method for preparing an ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology according to claim 6, characterized in that: In step 1, the substrate used to prepare the black matrix includes a glass substrate, an ITO conductive substrate or an inorganic thin film substrate with high light transmittance.

8. The method for preparing an ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology according to claim 6, characterized in that: In step 2, the black photoresist is evenly coated on the surface of the substrate by spin coating, screen printing or slit coating.

9. The method for preparing an ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology according to claim 6, characterized in that: In step 3, the black matrix forming method includes maskless grayscale exposure, laser direct writing and nanoimprinting.

10. The method for preparing an ultra-high resolution display pixel black matrix based on maskless grayscale exposure technology according to claim 6, characterized in that: In step 6, the luminescent material includes quantum dot material, organic luminescent material, inorganic phosphor, rare earth doped nanoparticles or dye molecules.

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