Method for preparing light-emitting microparticles based on laser regulation and control of substrate gradient wetting

Abstract

The invention relates to the technical field of preparation of photoelectric device materials, in particular to a method for preparing light-emitting microparticles based on laser regulation and control of substrate gradient wetting. Aiming at the problem that the industrialization requirements of high-precision patterning, high material utilization rate, high device performance and low production cost cannot be met at the same time in the prior art, the invention provides the following technical scheme: S1, substrate surface modification; s2, designing a pre-processing pattern; s3, constructing a wettability gradient through laser processing; s4, testing and verifying the hydrophilicity and hydrophobicity; s5, the solution is guided by a scraper to be self-assembled; and S6, performing temperature-controlled evaporation to realize directional arrangement of the particles. The wettability gradient of the substrate is precisely regulated and controlled through laser, high-precision patterning preparation of the light-emitting microparticles is achieved, the material utilization rate is increased, the production cost is reduced, particle arrangement and film forming quality are optimized, the light-emitting performance and stability of the device are enhanced, the device is adaptive to various substrates, materials and laser sources, compatibility is high, and research and development and mass production requirements can be met.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic device material preparation technology, and in particular to a method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting. Background Technology

[0002] In the fields of optoelectronic devices such as displays, lighting, and optical communications, developing high-performance, low-cost, and scalable luminescent material fabrication technologies is a core requirement for promoting the miniaturization, high resolution, and long lifespan of devices. Among these, perovskite materials, due to their superior optoelectronic properties such as high absorption coefficient, adjustable bandgap, high carrier mobility, and long carrier diffusion length, coupled with low raw material costs and compatibility with solution-based fabrication processes, have become key candidate materials for optoelectronic devices such as light-emitting diodes (LEDs) and solar cells. Especially in the field of perovskite LEDs, their theoretical luminous efficiency and display performance are significantly superior to traditional organic LEDs, demonstrating extremely high industrialization potential.

[0003] However, the performance advantages of perovskite materials can only be fully realized with suitable processing technologies. Currently, the mainstream preparation processes for perovskite luminescent microparticles and thin films all face insurmountable technical bottlenecks, which severely restrict the industrialization process of perovskite optoelectronic devices. The specific shortcomings are as follows: Spin coating: A commonly used laboratory preparation method, it suffers from low material utilization. Dual-source thermal evaporation: While it allows for precise control of film composition and thickness in a vacuum environment, it relies on expensive vacuum equipment and suffers from high energy consumption and low batch processing efficiency, making it difficult to balance preparation precision with the economic efficiency and feasibility of industrial production. Inkjet printing: Despite its high material utilization, it has extremely stringent requirements regarding ink viscosity, surface tension, and other performance parameters. Screen printing: Limited by the precision of the screen, it cannot achieve micron-level high-precision patterning; furthermore, minute fluctuations in squeegee pressure and movement speed can cause film thickness deviations exceeding 10%, making it difficult to meet the stringent requirements of optoelectronic devices for film thickness consistency and unsuitable for the production of high-definition display devices.

[0004] The shortcomings of existing processes not only lead to low production efficiency and high costs, but also directly cause problems with the performance and stability of perovskite devices. On the one hand, traditional processes cannot precisely control the arrangement of luminescent particles, easily resulting in grain boundary defects and particle agglomeration, which increases carrier scattering and non-radiative recombination losses, reduces device brightness and efficiency, and shortens device lifespan due to uneven film structure. On the other hand, perovskite materials are sensitive to humidity and oxygen, while traditional processes result in poor film density and numerous pores within the film, allowing external moisture and oxygen to easily penetrate and corrode the material, leading to material decomposition and degradation of luminescent performance. In summary, existing technologies cannot simultaneously meet the industrialization requirements of high-precision patterning, high material utilization, high device performance, and low production costs. Therefore, this invention proposes a method for producing luminescent microparticles that is simple, low-cost, and can achieve precise arrangement of luminescent microparticles. Summary of the Invention

[0005] The purpose of this invention is to address the problem in the prior art that it is impossible to simultaneously meet the industrialization requirements of high-precision patterning, high material utilization, high device performance, and low production cost, and to propose a method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting.

[0006] The technical solution of this invention: A method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting, characterized by comprising the following processing steps: S1. A hydrophobic reagent is coated on the substrate surface using chemical modification to form a uniform hydrophobic layer. The concentration of the hydrophobic reagent, the coating rate and the drying conditions are controlled to make the static water contact angle of the hydrophobic layer reach 100°-120°, giving the substrate initial low surface energy hydrophobicity, which provides a basis for subsequent construction of wettability differences. S2. Construct a preset pattern with a multi-layer nested grid shape. Based on the requirements of different regions in the preset pattern for substrate wettability and microparticle arrangement, design a scanning spacing with different density to make the preset pattern form a structure containing different wettability regions and a continuous wettability gradient. The preset pattern is integrated with the scanning spacing parameter to generate a laser processing path file; S3. Load the laser processing path file and selectively ablate and modify the hydrophobic substrate surface by adjusting the laser power, scanning speed, scanning spacing and pulse frequency. The hydrophobic layer in the laser-treated area is destroyed, exposing the intrinsic hydrophilic sites of the substrate on the one hand, and forming hydroxyl and carboxyl hydrophilic functional groups on the other hand. After processing, a continuous wettability gradient is formed on the substrate surface: the contact angle gradually changes from 0°-30° on the hydrophilic side to 100°-120° on the hydrophobic side. At the same time, the hydrophilic area treated by the laser forms a micron-level groove. S4. Use a contact angle measuring instrument to test the hydrophilicity and hydrophobicity of each area of ​​the substrate pattern after processing in S3. Select at least 3 test points in each area to measure the static water contact angle. Verify the consistency between the actual wettability of each region and the preset pattern described in S2, and confirm that a continuous and stable wettability gradient is formed between adjacent regions; S5. Prepare a luminescent microparticle precursor solution with uniformity, and add the luminescent microparticle precursor solution dropwise to one end of the substrate that has passed the verification in S4. A high-precision scraper is used to scrape along the substrate surface at a constant speed of 0.1-10 mm / s and a preset angle of 30°-60°. With the help of the thrust of the high-precision scraper and the wettability gradient of the substrate, the luminescent microparticle precursor solution is preferentially spread in the hydrophilic region of the laser processing. The difference in hydrophilic and hydrophobic surface energy restricts the diffusion of the luminescent microparticle precursor solution into the hydrophobic region. At the same time, the micron-level grooves in the hydrophilic region adsorb the luminescent microparticle precursor solution through capillary suction, while the hydrophobic region repels the luminescent microparticle precursor solution through the lotus leaf effect, until a solution film matching the hydrophilic pattern is formed. S6. Perform temperature-controlled evaporation treatment on the substrate containing the solution film; By utilizing the wettability gradient formed by the differences in laser scanning spacing, laser power, and scanning speed, a high-density nucleation site is formed in the hydrophilic region, which promotes the rapid concentration and arrangement of microparticles. The transition region guides solute molecules in the luminescent microparticle precursor solution to migrate along the direction of decreasing wettability through the surface energy gradient, thereby achieving directional movement of the microparticles. The hydrophobic region restricts crystal growth through boundary constraints, ultimately resulting in luminescent microparticles with stable morphology and regular edges.

[0007] Optionally, the hydrophobic reagent in S1 is any one of silica hydrophobic reagent, silane hydrophobic reagent, or fluoride hydrophobic reagent.

[0008] Optionally, the type of laser in S3 can be any one of femtosecond pulse laser, nanosecond laser, or continuous laser; The laser power is 100-700mW, the scanning speed is 2-50mm / s, and the pulse frequency is 1-5kHz.

[0009] Optionally, the depth of the hydrophilic region is 0.5-2 μm and the width is 1-5 μm.

[0010] Optionally, the scraper in S5 can be any one of a glass scraper, a metal scraper, a ceramic scraper, or a silicon wafer scraper; The parallelism error between the scraper and the substrate surface is ≤0.1mm; The luminescent microparticle precursor solution is any one of the following: CsPbI3 perovskite precursor solution, CsPbBr3 perovskite precursor solution, CsPbCl3 perovskite precursor solution, quantum dot precursor solution, or organic fluorescent molecule precursor solution. The particle size deviation of the solute particles in the precursor solution is ≤10%.

[0011] Optionally, the temperature-controlled evaporation described in S6 adopts a stepped heating process: the initial temperature is 25-30℃, maintained for 5-10 minutes, and then the temperature is increased to 60-120℃ at a rate of 1-5℃ / min, and held for 15-30 minutes. During the temperature-controlled evaporation process, the ambient humidity is controlled between 30% and 50%.

[0012] Optionally, the substrate is any one of copper plate, glass slide, silicon wafer, or flexible polymer substrate; If the substrate is a flexible polymer substrate, plasma pretreatment is required before coating the hydrophobic reagent in S2. The pretreatment parameters are: power 50-100W, treatment time 3-5min, which is used to enhance the adhesion between the hydrophobic layer and the substrate.

[0013] Optionally, the preset pattern in S2 includes an array pattern, a multi-layer nested grid pattern, or a custom shape pattern; When the pattern is a multi-layered nested grid, the scanning spacing is designed according to the particle arrangement requirements: the scanning spacing of the high-density particle arrangement area is 5-10μm, the scanning spacing of the directional guidance area is 10-50μm, and the scanning spacing of the restricted growth area is 50-100μm.

[0014] In summary, this application includes at least one of the following beneficial technical effects: This invention uses femtosecond pulsed laser to precisely control scanning parameters, constructing a continuous wettability gradient in one go, achieving a gradual change in contact angle from 0°-30° to 100°-120°. It can realize multi-layer nested grids or custom complex patterns, with an edge regularity error of ≤0.1mm. No additional photolithography is required, solving the problems of difficult patterning in spin coating, low precision in screen printing, and easy clogging of inkjet printing nozzles. Furthermore, by relying on scraper guidance and wettability gradient, the precursor solution spreads only in the hydrophilic region, improving material utilization; it eliminates the need for expensive equipment for dual-source thermal evaporation, reducing costs, and enables large-area uniform film formation, making it suitable for large-scale production. Furthermore, by guiding the orderly arrangement of particles through wettability gradient, carrier loss is reduced, and the external quantum efficiency of perovskite LEDs is improved; the dense thin film is tightly bonded, isolating water vapor and oxygen, and extending the half-life of the device at room temperature, thus solving the problems of low brightness and short lifespan of traditional processes. Furthermore, the substrate, hydrophobic reagent, laser source, and luminescent microparticles proposed in this invention can all be flexibly replaced. The operation involves only six steps, requires no complex maintenance, and can be used for both laboratory research and industrial production, supporting optoelectronic device applications in multiple fields. In summary, this invention enables high-precision patterning of luminescent microparticles by precisely controlling the substrate wettability gradient with laser, significantly improving material utilization and reducing production costs. At the same time, it optimizes the particle arrangement and film quality, significantly enhancing the luminescent performance and stability of the device. Furthermore, the process is adaptable to various substrates, materials, and laser sources, exhibiting strong compatibility and meeting both R&D and mass production needs, effectively overcoming the technical bottlenecks of traditional fabrication processes. Attached Figure Description

[0015] Figure 1 This is a flowchart of a method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting; Figure 2(a) is a schematic diagram of the pre-processed pattern in Example S2; Figure 2(b) is a photograph of the substrate after laser processing in Example S3; Figure 3(a) is a schematic diagram of the hydrophilic site array in the embodiment; Figure 3(b) is a schematic diagram of droplet distribution in the embodiment; Figure 4 This is a diagram showing the arrangement of CsPbI3 particles after evaporation in the example. Detailed Implementation

[0016] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0018] 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.

[0019] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Example like Figure 1 As shown, the present invention proposes a method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting, comprising the following processing steps: S1. Substrate Surface Modification: A hydrophobic reagent is coated onto the substrate surface using chemical modification methods to form a uniform hydrophobic layer. The concentration of the hydrophobic reagent, the coating rate, and the drying conditions are controlled to make the static water contact angle of the hydrophobic layer reach 100°-120°, giving the substrate initial low surface energy hydrophobicity and providing a basis for subsequent construction of wettability differences. The hydrophobic reagent can be any one of silica hydrophobic reagents, silane hydrophobic reagents, and fluoride hydrophobic reagents. In this embodiment, a silica hydrophobic reagent is selected. S2. Pre-processed pattern design: Construct a preset pattern with a multi-layer nested grid shape. Based on the requirements of different regions in the preset pattern for substrate wettability and micro-particle arrangement, design a scanning spacing with different density to make the preset pattern form a structure containing different wettability regions and a continuous wettability gradient. The preset pattern is integrated with the scanning distance parameter to generate a laser processing path file; the laser type is a femtosecond pulse laser, the laser power is 500mW, the scanning speed is 15mm / s, and the pulse frequency is 1kHz. S3. Laser processing to create wettability gradient: Load the laser processing path file and selectively ablate and modify the hydrophobic substrate surface by adjusting the laser power, scanning speed, scanning spacing and pulse frequency. The hydrophobic layer in the laser-treated area is destroyed, exposing the intrinsic hydrophilic sites of the substrate on the one hand, and forming hydroxyl and carboxyl hydrophilic functional groups on the other hand. After processing, a continuous wettability gradient is formed on the substrate surface: the contact angle gradually changes from 0°-30° on the hydrophilic side to 100°-120° on the hydrophobic side. At the same time, the hydrophilic area treated by the laser forms a micron-level groove. S4. Hydrophilicity and hydrophobicity test verification: The hydrophilicity and hydrophobicity of each area of ​​the substrate pattern after S3 processing is tested using a contact angle measuring instrument. At least 3 test points are selected in each area to measure the static water contact angle. Verify the consistency between the actual wettability of each region and the preset pattern described in S2, and confirm that a continuous and stable wettability gradient is formed between adjacent regions; S5. Scraper-guided solution self-assembly: Prepare a homogeneous luminescent microparticle precursor solution. The luminescent microparticle precursor solution can be any one of CsPbI3 perovskite precursor solution, CsPbBr3 perovskite precursor solution, CsPbCl3 perovskite precursor solution, quantum dot precursor solution, or organic fluorescent molecule precursor solution. In this embodiment, CsPbI3 perovskite precursor solution is selected. The luminescent microparticle precursor solution is dropped onto one end of the substrate that has passed the verification in S4. A high-precision glass scraper is used to scrape along the substrate surface at a constant speed of 0.1-10 mm / s and a preset angle of 30°-60°. With the help of the thrust of the high-precision scraper and the wettability gradient of the substrate, the luminescent microparticle precursor solution is preferentially spread in the hydrophilic region of the laser processing. The difference in hydrophilic and hydrophobic surface energy restricts the diffusion of the luminescent microparticle precursor solution into the hydrophobic region. At the same time, the micron-level grooves in the hydrophilic region adsorb the luminescent microparticle precursor solution through capillary suction, while the hydrophobic region repels the luminescent microparticle precursor solution through the lotus leaf effect, until a solution film matching the hydrophilic pattern is formed. S6. Temperature-controlled evaporation achieves directional particle arrangement: The substrate containing the solution film is subjected to temperature-controlled evaporation treatment; the temperature-controlled evaporation adopts a stepped heating process: the initial temperature is 27℃, maintained for 8 min, and then the temperature is increased to 100℃ at a rate of 3℃ / min and held for 25 min. The ambient humidity is controlled at 45% during the temperature-controlled evaporation process. By utilizing the wettability gradient formed by the differences in laser scanning spacing, laser power, and scanning speed, a high-density nucleation site is formed in the hydrophilic region, which promotes the rapid concentration and arrangement of microparticles. The transition region guides solute molecules in the luminescent microparticle precursor solution to migrate along the direction of decreasing wettability through the surface energy gradient, thereby achieving directional movement of the microparticles. The hydrophobic region restricts crystal growth through boundary constraints, ultimately resulting in luminescent microparticles with stable morphology and regular edges.

[0022] Furthermore, this embodiment takes the preparation of CsPbI3 luminescent microparticles for perovskite LEDs as an example.

[0023] Selected equipment and its parameters: Femtosecond pulsed laser: coherent Libra-HE, power 100-700mW; High-precision 3D moving stage: Zhuoli Hanguang ZT-80XYZ, X / Y / Z axis positioning accuracy ≤0.01mm, ensuring focus alignment; Computer control system: Equipped with SAMLight marking program to generate laser processing path; CCD microscopic observation system: Sanqiang TEDA TD-4KHU, 4K resolution; Ultrasonic cleaner: Gote Ultrasonic VGT-1860QTD, power 150W; Contact angle measuring instrument: Chongqing Sanke SK-CKA / B; Heating platform: Jinfeng JF-956, temperature control accuracy ±1℃, suitable for stepped heating; High-precision scraper: glass scraper, 2mm thick, parallelism error ≤0.1mm; Experimental materials and specifications: Substrate: Glass slide: 15mm×15mm×1mm; Hydrophobic reagent: 5% concentration silica hydrophobic solution; Anhydrous ethanol: purity ≥ 99.8%; CsPbI3 perovskite precursor solution: solute concentration 0.15 mol / L, particle size deviation ≤8%; Deionized water: resistivity ≥ 18.2 MΩ·cm Specific implementation steps

[0024] Substrate pretreatment Preliminary impurity removal: Place the glass slide in a beaker containing 99.8% anhydrous ethanol and soak and rinse for 2 minutes to remove large particles of dust and visible contaminants from the surface; Deep cleaning: Transfer the substrate to an ultrasonic cleaner, set the power to 350W and the frequency to 40kHz, and clean for 6 minutes; Drying and preparation: Remove the substrate and blow off any residual ethanol on the surface with a micro nitrogen gun at a flow rate of 5 L / min. Place it in a clean petri dish to avoid secondary contamination.

[0025] S1: Substrate surface modification Hydrophobic coating preparation: A spraying process was adopted, using a 0.5mm nozzle spray gun to uniformly coat the cleaned substrate surface with 5% silica hydrophobic liquid at a pressure of 0.2MPa and a spraying distance of 12cm. Drying control: Place the coated substrate in a room temperature environment for 10 minutes to ensure that the hydrophobic layer is completely dry; Hydrophobicity verification: Using an SK-CKA / B type contact angle meter, three test points were randomly selected on the substrate surface. The static water contact angles were measured to be 115°, 118°, and 120°, respectively. The hydrophobic layer modification was deemed qualified, and the substrate possessed initial low surface energy hydrophobicity.

[0026] S2: Pre-processed pattern design Pattern construction: Design a multi-layered nested grid preset pattern using AutoCAD software, and divide it into 3 functional areas; as shown in Figure 2; High-density particle arrangement area (central region): designed scanning spacing of 10μm; Orientation guidance area (intermediate transition layer): designed with a gradient scanning spacing of 50μm; Restricted growth region (edge ​​region): Designed scanning spacing of 100 μm; Path generation: Import the pattern and scanning spacing parameters into the SAMLight marking program to generate a laser processing path file with a path accuracy of ±0.005mm, ensuring that subsequent processing matches the preset design.

[0027] S3: Laser processing to create a wettability gradient Parameter settings: Turn on the femtosecond laser system, adjust the laser power to 500mW via the pre-optical path half-wave plate, and set the following in the SAMLight program: Scanning speed 15mm / s; Pulse frequency 1kHz; Load the processing path file generated by S2; Focus positioning: Fix the properly modified substrate onto a three-dimensional moving stage, monitor it in real time using a CCD microscopic observation system, and drive the X / Y / Z axes to adjust the substrate coordinates to: X=7.5mm, Y=7.5mm, Z=9mm, ensuring that the laser focus is accurately positioned in the center of the substrate processing area; Selective ablation: The laser is activated to ablate the substrate surface along a preset path. Laser-acted area: The hydrophobic layer is completely removed, exposing the intrinsic hydrophilic sites of the substrate, and at the same time forming a micron-scale groove with a depth of 1μm and a width of 3μm; The contact angle after processing is 22° in the hydrophilic region and 116° in the hydrophobic region, with a contact angle gradient change of 8° / mm between adjacent regions, forming a continuous wettability gradient. A physical image of the processed substrate is shown in Figure 2(b).

[0028] S4: Hydrophilicity / hydrophobicity test verification Contact angle testing: Using an SK-CKA / B type contact angle measuring instrument, three test points were selected in each of the three functional areas of the pattern processed by S3. The measured data are as follows:

[0029] Gradient verification: If the difference in contact angle gradient between adjacent regions is ≤8° / mm, the wettability gradient is determined to be continuous and stable, and the substrate can proceed to the next step.

[0030] S5: Scraper-guided solution self-assembly Solution addition: Using a 10 μL pipette, accurately add the 0.15 mol / L CsPbI3 precursor solution to the upper left corner of the substrate, 3 mm from the edge; Squeegee application: Handheld glass squeegee, parameter settings: Scraping speed 5mm / s; The scraper is at a 45° angle to the substrate; Scrape the coating horizontally from the top left corner to the bottom right corner, using the scraper's pushing force and the wettability gradient: The hydrophilic region has micron-sized grooves that adsorb the solution through capillary suction, forming a concave meniscus. The hydrophobic region repels the solution through the lotus leaf effect, causing the droplet to shrink into a bead shape; The hydrophilic-hydrophobic transition zone exhibits a wave-like progression, with the hydrophilic end spreading at a rate four times that of the hydrophobic end, ultimately forming a solution film that perfectly matches the nested grid pattern.

[0031] S6: Temperature-controlled evaporation achieves directional particle arrangement Stepped heating setup: Transfer the substrate containing the solution film to the heating stage and execute the following heating procedure: Initial stage: Keep warm at 28℃ for 8 minutes; Heating phase: Increase the temperature to 90℃ at a rate of 3℃ / min; Insulation stage: Insulate at 90℃ for 20 minutes; Environmental control: Maintain humidity at 40-45% to avoid abnormal crystallization; Directed crystallization process: Hydrophilic region (scanning interval 10μm): High surface energy, forming high-density nucleation sites, CsPbI3 particles rapidly concentrate and arrange, with a packing density ≥95%; Transition region (gradual spacing 50μm): The surface energy gradient guides solute molecules to migrate along the direction of decreasing wettability, and the particle orientation deviation is ≤2μm; Hydrophobic regions (100 μm spacing): Boundary-constrained crystal growth, particle edge regularity error ≤ 0.08 mm; Final product: CsPbI3 luminescent microparticles that closely match the multi-layer nested grid pattern are obtained, with individual particle diameter deviation ≤5% and thickness uniformity ≥92%.

[0032] Preparation effect verification Laser processing effect: CCD observation shows that a clear multi-layer nested grid of hydrophilic sites is formed on the substrate surface, as shown in Figure 3(a). The micron-level groove structure in the hydrophilic area is intact, with no hydrophobic layer residue. Solution spreading effect: After coating, the solution accurately fills the hydrophilic sites, forming a droplet distribution that matches the grid pattern, as shown in Figure 3(b). There is no solution residue in the hydrophobic areas, and the film thickness deviation is ≤4%. Particle arrangement effect: After evaporation, CsPbI3 particles are uniformly and densely arranged within the hydrophilic sites, such as... Figure 4 As shown, the particle size uniformity of the high-density region is ≥95%, and the particle arrangement direction of the oriented region is completely consistent with the wettability gradient direction, which meets the requirements of perovskite LED light-emitting layer for low defects and high order. Performance verification: The CsPbI3 luminescent microparticles prepared by this method have a luminescence intensity deviation of ≤6%, a device half-life of ≥2800 hours at room temperature, and a material utilization rate of 88%, which meets the core requirements of industrialization for high performance and low cost.

[0033] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting, characterized in that, The following processing steps are included: S1. A hydrophobic agent is coated onto the substrate surface using chemical modification methods to form a uniform hydrophobic layer; By adjusting the concentration of hydrophobic reagent, coating rate and drying conditions, the static water contact angle of the hydrophobic layer is made to reach 100°-120°, giving the substrate initial low surface energy hydrophobicity, which provides a basis for subsequent construction of wettability differences. S2. Construct a preset pattern with a multi-layer nested grid shape. Based on the requirements of different regions in the preset pattern for substrate wettability and microparticle arrangement, design a scanning spacing with different density to make the preset pattern form a structure containing different wettability regions and a continuous wettability gradient. The preset pattern is integrated with the scanning spacing parameter to generate a laser processing path file; S3. Load the laser processing path file and selectively ablate and modify the hydrophobic substrate surface by adjusting the laser power, scanning speed, scanning spacing and pulse frequency. The hydrophobic layer in the laser-treated area is destroyed, exposing the intrinsic hydrophilic sites of the substrate on the one hand, and forming hydroxyl and carboxyl hydrophilic functional groups on the other hand. After processing, a continuous wettability gradient is formed on the substrate surface: the contact angle gradually changes from 0°-30° on the hydrophilic side to 100°-120° on the hydrophobic side. At the same time, the hydrophilic area treated by the laser forms a micron-level groove. S4. Use a contact angle measuring instrument to test the hydrophilicity and hydrophobicity of each area of ​​the substrate pattern after processing in S3. Select at least 3 test points in each area to measure the static water contact angle. Verify the consistency between the actual wettability of each region and the preset pattern described in S2, and confirm that a continuous and stable wettability gradient is formed between adjacent regions; S5. Prepare a luminescent microparticle precursor solution with uniformity, and add the luminescent microparticle precursor solution dropwise to one end of the substrate that has passed the verification in S4. A high-precision scraper is used to scrape along the substrate surface at a constant speed of 0.1-10 mm / s and a preset angle of 30°-60°. With the help of the thrust of the high-precision scraper and the wettability gradient of the substrate, the luminescent microparticle precursor solution is preferentially spread in the hydrophilic region of the laser processing. The difference in hydrophilic and hydrophobic surface energy restricts the diffusion of the luminescent microparticle precursor solution into the hydrophobic region. At the same time, the micron-level grooves in the hydrophilic region adsorb the luminescent microparticle precursor solution through capillary suction, while the hydrophobic region repels the luminescent microparticle precursor solution through the lotus leaf effect, until a solution film matching the hydrophilic pattern is formed. S6. Perform temperature-controlled evaporation treatment on the substrate containing the solution film; By utilizing the wettability gradient formed by the differences in laser scanning spacing, laser power, and scanning speed, a high-density nucleation site is formed in the hydrophilic region, which promotes the rapid concentration and arrangement of microparticles. The transition region guides solute molecules in the luminescent microparticle precursor solution to migrate along the direction of decreasing wettability through the surface energy gradient, thereby achieving directional movement of the microparticles. The hydrophobic region restricts crystal growth through boundary constraints, ultimately resulting in luminescent microparticles with stable morphology and regular edges.

2. The method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting according to claim 1, characterized in that, The hydrophobic reagent in S1 is any one of silica hydrophobic reagent, silane hydrophobic reagent, or fluoride hydrophobic reagent.

3. The method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting according to claim 1, characterized in that, The laser type in S3 is any one of femtosecond pulse laser, nanosecond laser, or continuous laser; The laser power is 100-700mW, the scanning speed is 2-50mm / s, and the pulse frequency is 1-5kHz.

4. The method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting according to claim 1, characterized in that, The hydrophilic region has a depth of 0.5-2 μm and a width of 1-5 μm.

5. The method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting according to claim 1, characterized in that, The scraper in S5 can be any one of a glass scraper, a metal scraper, a ceramic scraper, or a silicon wafer scraper; The parallelism error between the scraper and the substrate surface is ≤0.1mm; The luminescent microparticle precursor solution is any one of the following: CsPbI3 perovskite precursor solution, CsPbBr3 perovskite precursor solution, CsPbCl3 perovskite precursor solution, quantum dot precursor solution, or organic fluorescent molecule precursor solution. The particle size deviation of the solute particles in the precursor solution is ≤10%.

6. The method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting according to claim 1, characterized in that, The temperature-controlled evaporation described in S6 adopts a stepped heating process: the initial temperature is 25-30℃, maintained for 5-10 minutes, and then the temperature is increased to 60-120℃ at a rate of 1-5℃ / min, and held for 15-30 minutes. During the temperature-controlled evaporation process, the ambient humidity is controlled between 30% and 50%.

7. The method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting according to claim 1, characterized in that, The substrate is any one of copper plate, glass slide, silicon wafer, or flexible polymer substrate; If the substrate is a flexible polymer substrate, plasma pretreatment is required before coating the hydrophobic reagent in S2. The pretreatment parameters are: power 50-100W, treatment time 3-5min, which is used to enhance the adhesion between the hydrophobic layer and the substrate.

8. The method for preparing luminescent microparticles based on laser-controlled substrate gradient wetting according to claim 1, characterized in that, The preset pattern mentioned in S2 includes array pattern, multi-layer nested grid pattern or custom shape pattern; When the pattern is a multi-layered nested grid, the scanning spacing is designed according to the particle arrangement requirements: the scanning spacing of the high-density particle arrangement area is 5-10μm, the scanning spacing of the directional guidance area is 10-50μm, and the scanning spacing of the restricted growth area is 50-100μm.

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