Fluorescent pattern preparation method based on glass perovskite composite material

Abstract

The invention relates to a fluorescent pattern preparation method based on a glass perovskite composite material, and belongs to the technical field of micro-nano processing and fluorescent materials. The method aims to solve the problem that the conventional perovskite material cannot be compatible with a standard photoetching process due to the fact that the ionic crystal characteristic of the perovskite material is easily dissolved and damaged by polar solvents such as a developing solution and the like in a photoetching patterning process. Glass perovskite powder with high chemical stability is prepared by wrapping a perovskite luminous body in an inorganic glass matrix, and the glass perovskite powder is uniformly compounded with a negative wet film photoresist to form a fluorescent composite photoresist; and then preparing a high-resolution fluorescent pattern on the substrate by adopting standard photoetching processes such as spin coating, exposure and development. The obtained fluorescent pattern shows stable luminescence performance under excitation of 365 nm ultraviolet light, and has good process compatibility and environmental stability while keeping high photoluminescence efficiency. The method is suitable for the fields of micro display, anti-counterfeiting encryption, photoelectric integration and the like.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of micro-nano fabrication technology and optoelectronic materials technology, and specifically relates to a method for preparing fluorescent micropatterns by combining highly stable glass perovskite fluorescent materials with standard photolithography processes. Background Technology

[0002] Fluorescent micropatterns, serving as information carriers or functional units, are crucial in modern optoelectronic fields such as high-density storage, microdisplays, anti-counterfeiting labels, and biochips. The core challenge in their fabrication lies in how to pattern high-performance fluorescent materials onto various substrates with high precision, high resolution, and process compatibility.

[0003] Currently, to achieve this goal, the industry has mainly explored several technical paths, but all have inherent limitations. Organic dyes and traditional phosphors were among the earliest materials used. Although organic dyes are easy to process, their photostability is generally poor, and they are prone to photodegradation and fluorescence quenching during ultraviolet exposure in photolithography and subsequent use. Traditional inorganic phosphors, such as rare-earth-doped phosphors, have high chemical stability, but their particle size is mostly on the micrometer scale, making it difficult to achieve sub-micrometer high-resolution patterns through fine photolithography. In addition, the uniform dispersion of micrometer-sized particles in photoresist is also extremely challenging, easily leading to rough patterns or uneven performance.

[0004] In recent years, perovskite quantum dots have been considered highly promising fluorescent materials due to their superior luminescent properties, such as high color purity, wide color gamut, and wavelength tunability, and their application in patterning has been explored. However, the ionic crystal nature of these materials presents a fundamental weakness. They are fragile in the wet etching steps essential to photolithography, especially sensitive to the polar solvents commonly used in development and cleaning processes, easily leading to dissolution, structural damage, or severe fluorescence quenching. To circumvent this problem, existing solutions often require the introduction of complex additional encapsulation layers or the shift to non-standard dry etching processes, which significantly increases process complexity and manufacturing costs, making it difficult to integrate them into mature, efficient standard photolithography production lines.

[0005] Besides the limitations of the material system, other non-photolithography patterning technologies, such as inkjet printing or laser direct writing, while avoiding wet etching, generally face their own bottlenecks. These technologies are usually limited in pattern resolution, making it difficult to stably achieve fine lines below ten micrometers. They may also be accompanied by problems such as rough pattern edges and low material loading, failing to meet the stringent requirements of high-end microelectronic devices for pattern precision and consistency.

[0006] The purpose of this invention is to overcome the above-mentioned defects and provide a method for preparing high-stability, high-resolution fluorescent patterns that can maintain the excellent luminescent properties of perovskite materials and be fully compatible with standard photolithography processes. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing fluorescent patterns based on glass perovskite composite materials. By designing the material structure and optimizing the process parameters, the method achieves stable patterning of perovskite fluorescent materials in a standard photolithography process, thereby obtaining high-resolution and high-stability fluorescent patterns.

[0008] To achieve the above objectives, the technical concept of the present invention is as follows: First, a glass perovskite luminescent material is encapsulated and confined within a glass matrix to prepare a glass perovskite powder with significantly improved chemical stability. Second, this powder is used as a functional filler and uniformly composited with a negative wet film photoresist to prepare a fluorescent composite photoresist. Finally, the fluorescent composite photoresist is patterned onto the substrate surface using optimized standard photolithography process parameters.

[0009] Through the above technical solution, this invention achieves effective protection of perovskite fluorescent materials during wet processing steps such as development, without introducing additional encapsulation layers or non-standard processes, while balancing high luminous efficiency and good process compatibility.

[0010] This technical solution is implemented through the following steps: S1. Preparation of fluorescent composite photoresist: A glass-structured perovskite luminescent powder with a specific composition is mixed with a selected negative wet film photoresist colloid (e.g., negative photoresist) in a predetermined mass ratio, and a uniform and stable suspension is formed by mechanical stirring and ultrasonic dispersion. S2. Substrate Coating and Soft Baking: After mixing and standing for 20 minutes, the upper composite photoresist is applied to the clean substrate surface using a spin coating method. Spin coating is performed at 5000 rpm for 30 seconds to obtain a uniform photoresist film of the desired thickness. Subsequently, a hot plate soft baking is immediately performed to remove most of the solvent and allow the photoresist film to initially cure and set. S3. Mask Exposure: Place the softened substrate under the photolithography machine, align it using a mask with the target pattern, and use 365nm wavelength ultraviolet light with an exposure dose of 80-120mJ / cm². 2 The photoresist in the exposed area undergoes a photocrosslinking reaction, resulting in a change in its chemical structure; S4. Development and Pattern Formation: Immerse the exposed substrate in the developer solution compatible with the photoresist for 30-45 seconds, accompanied by gentle agitation. During this process, the photoresist in the unexposed areas, along with the phosphor powder within it, is dissolved and removed, while the exposed and cured areas remain, thus accurately reproducing the fluorescent pattern designed by the photomask on the substrate. S5. Post-processing and performance characterization: After development, the substrate is cleaned and dried. Baking at 100°C for 2 minutes may be performed as needed to further enhance the adhesion and stability of the pattern. Finally, excitation with 365nm UV light should produce bright, well-defined fluorescence in the patterned areas. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the fluorescent pattern preparation process based on glass perovskite composite material in an embodiment of the present invention; Figure 2 The fluorescent pattern sample prepared in Comparative Example 1 is shown as a fluorescence image under 365nm ultraviolet light excitation. Figure 3 The fluorescent pattern sample prepared in Comparative Example 2 is shown as a fluorescence image under 365nm ultraviolet light excitation. Detailed Implementation

[0012] To better understand the objectives, technical solutions, and advantages of this invention, the above technical solutions will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and do not constitute any limitation on the scope of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0013] In the context of this invention, a wide range of raw materials can be selected. To support the scope of the claims, general concepts of some key raw materials are now explained: The term "glass perovskite" refers to an inorganic composite fluorescent material characterized by perovskite crystal structural units being encapsulated, embedded, or confined within an inorganic glass matrix network. This glass matrix serves as both physical isolation and chemical protection. Preferably, it is a glass perovskite with a silicate glass matrix; in a preferred embodiment of the invention, it is specifically cesium lead bromide (CsPbBr3) silicate glass.

[0014] The term "photoresist" refers to a polymeric colloidal material that is sensitive to light of a specific wavelength and whose solubility changes predictably after exposure. Examples include, but are not limited to, epoxy resin systems, acrylate systems, and phenolic resin-diazonaphthoquinone system photoresists. It is used to transfer patterns from a photomask to a substrate via photolithography. A wet-film negative acrylate system photoresist is preferred because it undergoes cross-linking and curing after exposure, which is more conducive to firmly locking the glass perovskite powder, used as a filler, within the pattern.

[0015] The "fluorescent pattern" refers to a microscopic pattern formed on a substrate by the method of the present invention, consisting of a cured photoresist containing glass perovskite powder. The pattern emits fluorescence under ultraviolet light excitation at a specific wavelength, and its linewidth or feature size can be between 100 micrometers and 1000 micrometers, preferably between 100 micrometers and 1000 micrometers.

[0016] The following description uses specific examples and comparative models to illustrate the point.

[0017] Example 1 This embodiment provides a method for preparing fluorescent patterns based on glass perovskite composite materials, the steps of which are as follows: S1. In a clean 20ml amber glass bottle, accurately weigh 1.00g of glass perovskite powder using an electronic balance. Then, accurately pipette 5.00ml of photoresist stock solution and add it to the same bottle. This ratio corresponds to a powder to photoresist solids mass ratio of approximately 1:2.5. Tighten the cap and place the bottle on a vortex mixer, continuously oscillating at maximum speed for 5 minutes. This step aims to initially wet the powder and break up large agglomerates.

[0018] S2. Place the brown bottle in an ice-water bath to prevent localized overheating during ultrasound, which could alter the colloidal properties or cause solvent evaporation. Immerse the ultrasound probe approximately 1 cm below the liquid surface. Set the ultrasound machine to pulse mode (2 seconds on, 2 seconds off), with a power setting of 300 W and dynamic ultrasound, for a total treatment time of 30 minutes. After treatment, drop a sample onto a 1 cm glass slide and observe it under an optical microscope. If the powder particles are confirmed to be uniformly distributed as monodisperse or extremely small aggregates, with no obvious aggregates larger than 5 μm, it is considered "uniformly dispersed," and the fluorescent composite photoresist is obtained.

[0019] S3. Take approximately 0.5 mL of the composite photoresist and drop it onto the center of the pretreated glass slide. The spin coating program is set as follows: First stage, spin at 500 rpm for 10 seconds to spread the photoresist; Second stage, rapidly accelerate to 4000 rpm and hold for 30 seconds to form a uniform photoresist film. After spin coating, immediately transfer the glass slide to a hot plate preheated to 100°C and bake for 90 seconds.

[0020] S4. Using a calibrated contact lithography machine, align the resist-coated glass slide with the photomask. Expose the image using 365nm wavelength ultraviolet light, controlling the exposure time to achieve an energy density of 110mJ / cm² in the exposed area. 2 After exposure, the silicon wafer is completely immersed in a glass dish containing developer and left to stand for 40 seconds. Then, the wafer is transferred to a second tank of fresh developer and rinsed for 10 seconds to completely stop the development reaction. Finally, the slide is placed on a hot plate and baked at 110°C for 10 minutes to complete the cross-linking and curing of the photoresist, enhancing pattern adhesion.

[0021] Performance Testing: Using a fluorescence spectrophotometer equipped with an integrating sphere, the absolute photoluminescence quantum yield (PLQY) of the original glass perovskite powder and the patterned film prepared in Example 1 were tested under the same 365 nm excitation conditions. The PLQY of the original powder was 65.0%, and the PLQY of the patterned film prepared in Example 1 was 53.7%. Calculations showed that after the entire process of composite, coating, and photolithography, the luminous efficiency of the final pattern relative to the original powder was 82.7% (i.e., 53.7% / 65.0% × 100%). This statement of "attenuation to 82.7%" specifically refers to this relative PLQY retention rate. After storing the sample in a constant temperature and humidity chamber (25°C, 60%RH) for 24 hours, the fluorescence intensity retention rate was greater than 95%. Comparative Example 1: The powder loading was increased to 1.5 g. This comparative example aims to investigate the effect of increasing the powder loading on the luminescence performance of the final fluorescent pattern under the same ultrasonic dispersion conditions.

[0022] S1. In a clean 20mL brown glass bottle, accurately weigh 1.50g (different from 1.00g in Example 1) of glass perovskite powder using an electronic balance. Then, accurately add 5.00mL of photoresist stock solution to the same bottle using a pipette. Tighten the cap and place the bottle on a vortex mixer, vortexing continuously at maximum speed for 5 minutes.

[0023] S2. The brown bottle was placed in an ice-water bath and treated using the same ultrasonic parameters as in Example 1: the probe was immersed approximately 1 cm below the liquid surface, the ultrasonic instrument was set to pulse mode (2 seconds of operation followed by a 2-second interval), the power was set to 300W, and the total treatment time was 30 minutes. After treatment, samples were taken for microscopic examination to confirm that a uniformly dispersed state was achieved, resulting in a high-load fluorescent composite photoresist.

[0024] S3. All parameters (substrate, rotation speed, temperature, time, exposure dose, etc.) of the subsequent spin coating, soft baking, exposure, development and post-baking steps are completely consistent with those of Example 1.

[0025] S4. Performance Testing: Under the same conditions, the PLQY of the patterned film was tested using a fluorescence spectrophotometer. The PLQY of Comparative Example 1 film was measured to be 56.2%. The retention rate relative to the original powder PLQY (65.0%) was 86.5% (i.e., 56.2% / 65.0%×100%). After storing the sample in a constant temperature and humidity chamber (25°C, 60%RH) for 24 hours, the fluorescence intensity retention rate was greater than 95%.

[0026] Conclusion: In a given photoresist system, there exists a saturation point for the powder content. Beyond this point, the added powder may not be effectively dispersed and encapsulated by the colloid, forming optical scattering centers or agglomerates. Furthermore, it is more easily lost during development, leading to a decrease in effective luminescence efficiency. This demonstrates that the powder-to-photoresist ratio needs optimization.

[0027] Comparative Example 2: Increase the powder loading to 2g This comparative example aims to investigate the limiting effect of a further significant increase in powder loading on the photolithographic patterning process and luminescence performance.

[0028] S1. In a clean 20ml brown glass bottle, accurately weigh 2.00g of glass perovskite powder using an electronic balance. Then, accurately add 5.00mL of photoresist stock solution to the same bottle using a pipette. Due to the extremely large amount of powder, the mixture is a high-viscosity paste, and its flowability remains extremely poor even after vortexing for 5 minutes.

[0029] S2. In an ice-water bath, attempt to disperse the mixture for 30 minutes using the same ultrasonic parameters as in Example 1 (300W, pulse mode). After treatment, the colloid viscosity was extremely high, and microscopic examination of samples revealed a large number of undispersible powder agglomerates (size >10μm).

[0030] S3. Due to the poor fluidity of the colloid, spin coating is extremely difficult, and the resulting film is obviously uneven and has a rough surface.

[0031] S4. The subsequent photolithography and development processes are the same as in Example 1. After development, it was found that the edges of the pattern were rough and some areas showed delamination.

[0032] Performance testing: The PLQY of the patterned area was tested under the same conditions. The PLQY of the comparative example 2 film was only 60.2%, with a retention rate as low as 92.7% relative to the original powder. The 24-hour stability test showed that its fluorescence intensity retention rate was still greater than 95% (indicating that the powder itself is stable, but the process compatibility has deteriorated).

[0033] Conclusion: When the ratio of photoresist to powder is severely imbalanced (excessive powder), it directly leads to the deterioration of the basic rheological properties of the composite photoresist, making it unable to meet the requirements of the homogenization process. Even with forced processing, uneven dispersion and poor pattern transfer quality will still occur, but the attenuation of powder photoluminescence intensity can be alleviated.

[0034] Comparative Example 3: The effect of insufficient dispersion process (mechanical stirring only) on luminous efficiency This comparative example aims to demonstrate that, with the same powder ratio, optimal luminescence performance cannot be obtained without the crucial step of ultrasonic dispersion.

[0035] S1. In a clean 20mL brown glass bottle, weigh out 1.50g of glass perovskite powder and 5.00mL of photoresist solution, the same as in Comparative Example 1.

[0036] S2. The key difference in this comparative example is that only mechanical stirring is performed, without ultrasonic treatment. The mixture is placed on a magnetic stirrer and stirred continuously at 800 rpm for 60 minutes at room temperature (the total energy consumption time is comparable to ultrasonic treatment plus vortex mixing).

[0037] S3. After stirring, samples were taken for microscopic examination. Under an optical microscope, a large number of powder agglomerates with sizes ranging from 5 to 20 μm were observed, indicating that the powder had not achieved a "uniformly dispersed" state.

[0038] S4. All parameters for subsequent spin coating, soft baking, exposure, development and post-baking steps are consistent with those in Example 1.

[0039] S5. Performance Testing: The PLQY of the obtained patterned film was tested. The PLQY of Comparative Example 3 film was measured to be 53.6%, with a retention rate of 82.6% relative to the original powder. 24-hour stability testing showed that its fluorescence intensity retention rate was greater than 95%.

[0040] Conclusion: The composite photoresist prepared by mechanical stirring alone exhibited a significantly lower luminous efficiency retention rate (82.6%) than the corresponding sample prepared by ultrasonic dispersion (Comparative Example 1, 86.5%). This directly and strongly demonstrates that ultrasonic dispersion is crucial for breaking powder agglomeration and achieving uniform dispersion at the micro-nano scale. It is an indispensable key step in obtaining high-luminous-efficiency composite photoresists, rather than an optional conventional mixing method.

[0041] Table 1: Summary of parameters and results for key embodiments and comparative examples

Claims

1. A method for preparing a fluorescent pattern based on a glass perovskite composite material, characterized by, The method comprises the following steps: S1. Preparing a fluorescent composite photoresist: mixing glass-matrix-encapsulated perovskite powder and negative wet film photoresist in a predetermined ratio, and performing dispersion treatment to obtain a uniformly dispersed fluorescent composite photoresist; S2. Substrate coating and soft baking: coating the fluorescent composite photoresist on a substrate surface to form a photoresist film, and performing soft baking treatment; S3. Mask exposure: performing ultraviolet exposure on the soft-baked photoresist film using a mask plate to cause a photocrosslinking reaction in the exposed area; S4. Developing: developing the exposed substrate to remove the uncured area and form a fluorescent pattern on the substrate; Optionally, the method further comprises step S5: post-baking treatment to enhance the adhesion and stability of the fluorescent pattern.

2. The method of claim 1, wherein, The dispersion treatment in step S1 comprises mechanical stirring and ultrasonic dispersion, and the ultrasonic dispersion is performed under temperature control, with the system temperature being not higher than 30°C during the dispersion process.

3. The method according to claim 1 or 2, characterized in that, The mixing ratio of the glass perovskite powder to the negative wet film photoresist is 1 g of glass perovskite powder to 3-8 ml of photoresist stock solution.

4. The method of claim 1, wherein, The coating in step S2 adopts a two-stage spin coating process: The first stage is rotating at 500-1000 rpm for 5-15 seconds for colloid spreading; The second stage is rotating at 3000-6000 rpm for 20-40 seconds for forming a uniform photoresist film; The soft baking temperature is 90-120°C, and the time is 60-120 seconds.

5. The method of claim 1, wherein, The wavelength of the ultraviolet exposure in step S3 is 365 nm, and the exposure dose is 80-120 mJ / cm 2 .

6. The method of claim 1, wherein, The developing solution in step S4 is an organic solvent developing solution matched with the negative wet film photoresist, and the developing time is 30-60 seconds.

7. A fluorescent composite photoresist, characterized by, The method comprises glass-matrix-encapsulated perovskite powder and negative wet film photoresist, and the perovskite powder is uniformly dispersed in the photoresist in a monodisperse or small-agglomerate form, with an equivalent particle size of not more than 5 μm.

8. A fluorescent pattern, characterized in that The fluorescent pattern is prepared by the method of any one of claims 1-6, emits fluorescence under 365 nm ultraviolet excitation, has an emission peak position of 500-530 nm, a photoluminescence quantum yield of not less than 80% of the original glass perovskite powder, a fluorescent intensity retention rate of not less than 90% after being stored at 25°C and 60% relative humidity for 30 days, and a linewidth or characteristic size of 100 μm-1 mm.

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