ZnO microparticle patterning method, patterned ZnO film and application

Abstract

The application belongs to the technical field of functional materials, and particularly relates to a ZnO micro-nanoparticle patterning method, a patterned ZnO film and application. The ZnO micro-nanoparticle patterning method comprises the following steps: preparing ZnO micro-nanoparticles with positive charges on the surface; grafting negative charge groups on the surface of the ZnO micro-nanoparticles to obtain a dispersion liquid of modified ZnO particles; obtaining a substrate with negative charges on the surface, and preparing a wet film of the dispersion liquid on the substrate with negative charges on the surface; and performing ultraviolet light irradiation treatment on the wet film through a mask to obtain a patterned ZnO film. The method is suitable for not only rigid substrates with high temperature resistance, but also flexible substrates with low temperature resistance, is simple to operate, has no special requirements on the operating environment, is mild in conditions, and is low in cost. Different patterned ZnO films can be prepared by adjusting the mask pattern, and the ultraviolet light irradiation treatment is high in efficiency and can quickly prepare large-area patterned ZnO films.

Description

Technical Field

[0001] This application belongs to the field of functional materials technology, and in particular relates to a method for patterning ZnO micro and nanoparticles, patterned ZnO films and their applications. Background Technology

[0002] Zinc oxide (ZnO) is a typical wide-bandgap (3.2 eV) and high exciton binding energy (60 meV) semiconductor material with diverse surface morphologies and unique physicochemical properties. It is widely used in photodetectors, ultraviolet light-emitting diodes, gas sensors, and fuel-sensitized batteries. Controllable deposition of ZnO micro / nanoparticles in specific regions is an important approach to further enhance the functionality of ZnO devices.

[0003] Currently, there are three main methods for patterning ZnO micro / nanoparticles: vertical pulling, laser-induced, and template-assisted methods. Vertical pulling involves vertically pulling a substrate from a particle suspension, spontaneously forming periodic stripe structures along a three-phase contact line with uniform energy. However, this method can only create stripe patterns and cannot form other patterns. Laser-induced methods use a laser to generate high energy at a spot, heating a local fluid and causing the surrounding micro / nanoparticles to aggregate. Specific patterns are formed by moving the spot. However, this method is limited by the spot size, making the fabrication of large-area patterned particles time-consuming and reliant on expensive laser equipment. Template-assisted methods form micro / nanoparticle patterns through a specific bond between the microstructure on the template surface and the micro / nanoparticles, enabling large-area fabrication. However, this method relies on the special structure of the template surface, and template fabrication typically involves photolithography or nanoimprinting processes, resulting in high costs.

[0004] Therefore, the existing large-area ZnO micro / nano particle patterning technology needs further improvement. Summary of the Invention

[0005] The purpose of this application is to provide a method for patterning ZnO micro / nanoparticles, a patterned ZnO film and its application, which aims to address, to some extent, the problem that existing large-area ZnO micro / nanoparticle patterning technology needs further improvement.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a method for patterning ZnO micro / nanoparticles, comprising the following steps:

[0008] Preparation of ZnO micro / nanoparticles with positive surface charge;

[0009] Negatively charged groups were grafted onto the surface of the ZnO micro / nano particles to obtain a dispersion of modified ZnO particles.

[0010] Obtain a substrate with a negatively charged surface, and form a wet film of the dispersion on the substrate with a negatively charged surface;

[0011] A patterned ZnO film is obtained by irradiating the wet film with ultraviolet light using a photomask.

[0012] In some possible implementations, the method for preparing positively charged ZnO micro / nanoparticles includes obtaining the positively charged ZnO micro / nanoparticles by thermally decomposing a zinc oxide precursor material.

[0013] In some possible implementations, the method of grafting the negatively charged groups onto the surface of the ZnO micro / nanoparticles includes: mixing the ZnO micro / nanoparticles with an organic compound carrying negatively charged groups in a solvent, separating and washing them to obtain a dispersion of the modified ZnO particles.

[0014] In some possible implementations, the conditions for the ultraviolet irradiation treatment include irradiation for 10 to 30 seconds under ultraviolet light wavelengths of 100 to 365 nm.

[0015] In some possible implementations, the average particle size of the ZnO micro / nanoparticles is 100 nm to 4 μm.

[0016] In some possible implementations, the negatively charged group includes at least one of a carboxylic acid group, a carboxylate group, a sulfonic acid group, a sulfonate group, and an alkyd group.

[0017] In some possible implementations, the mass ratio of the ZnO micro / nanoparticles to the organic matter is 1:(0.1 to 0.3).

[0018] In some possible implementations, the surface of the modified ZnO particles is grafted with at least one of carboxylic acid groups and carboxylate groups.

[0019] In some possible implementations, the organic compound includes at least one of sodium citrate and potassium citrate.

[0020] In some possible implementations, the negatively charged substrate includes at least one of a glass substrate, a silicon substrate, and polyvinyl chloride.

[0021] In some possible implementations, the method for obtaining a substrate with a negatively charged surface includes: after obtaining the substrate, performing plasma treatment on the substrate to obtain the substrate with a negatively charged surface.

[0022] In some possible implementations, the concentration of the dispersion is 10–40 mg / mL.

[0023] In some possible implementations, the average thickness of the wet film is 150–200 μm.

[0024] Secondly, this application provides a patterned ZnO film, which is prepared according to the above method. The surface of the patterned ZnO film close to the substrate is bonded to the substrate by electrostatic adsorption, and the surface away from the substrate is bonded by zinc ion bonding sites.

[0025] In some possible implementations, the average thickness of the patterned ZnO film is 100 nm to 20 μm.

[0026] Thirdly, this application provides an application of the above-mentioned patterned ZnO film, applying the patterned ZnO film to at least one of the fields of UV photodetectors, gas sensors, and ultraviolet light absorption plates.

[0027] The ZnO micro / nanoparticle patterning method provided in the first aspect of this application involves a wet film region irradiated with ultraviolet light. Under the influence of ultraviolet light, the negatively charged groups modified on the surface of the ZnO micro / nanoparticles are decomposed, causing the surface potential of the ZnO micro / nanoparticles to return to positive charge. This facilitates their deposition on the negatively charged substrate surface via electrostatic adsorption. Furthermore, the ZnO micro / nanoparticles themselves readily undergo photocorrosion under ultraviolet light irradiation, continuously releasing zinc ions during the irradiation process. These zinc ions serve as bonding sites. Bonds are formed between the negatively charged groups and the zinc ions, thereby inducing bonding between the modified ZnO particles. Therefore, through the combined effects of electrostatic adsorption and the bonding force between negatively charged groups and zinc ions, the ZnO micro / nanoparticles in the UV-irradiated areas are stably bonded to the electronegative substrate. In the areas shielded by the mask and not irradiated by UV light, electrostatic repulsion exists between the electronegative ZnO micro / nanoparticles and the electronegative substrate, allowing the ZnO micro / nanoparticles to be easily removed from the substrate surface, thus forming a patterned ZnO film. Furthermore, the ZnO micro / nanoparticles used are already crystalline, eliminating the need for subsequent annealing. UV patterning is suitable not only for high-temperature resistant rigid substrates such as glass but also for low-temperature resistant flexible substrates such as PVC. It eliminates the need for photoresist, is simple to operate, has no special environmental requirements, and offers mild preparation conditions at a low cost. Different patterned ZnO films can be fabricated by adjusting the mask pattern, and due to the high efficiency of UV irradiation, large-area patterned ZnO films can be rapidly prepared.

[0028] The patterned ZnO film provided in the second aspect of this application is prepared by the above-described method. Originally positively charged ZnO micro / nano particles are modified with negatively charged groups. Under ultraviolet light irradiation, these negatively charged groups decompose, causing the surface potential of the ZnO micro / nano particles to return to positive charge. They then bind to the negatively charged substrate surface through electrostatic adsorption. Furthermore, during ultraviolet light irradiation, the ZnO micro / nano particles undergo photocorrosion, continuously releasing zinc ions. Bonds are formed between the negatively charged groups and zinc ions, with the zinc ions acting as bonding sites. This causes the modified ZnO particles to bond away from the substrate surface through these zinc ion bonding sites, forming a film layer. Therefore, the patterned ZnO film formed by the dual effects of electrostatic adsorption and zinc ion bonding sites in this application exhibits good film stability, uniformity, and flatness. Moreover, the pattern, thickness, and area of ​​the patterned ZnO film can be flexibly controlled to meet different application requirements.

[0029] The patterned ZnO film provided in the third aspect of this application, due to the rapid photocurrent response of zinc oxide under UV light irradiation, can be used to fabricate devices such as UV photodetectors and gas sensors. Furthermore, zinc oxide can absorb ultraviolet light, therefore the patterned ZnO film can be applied to ultraviolet light absorbing plates such as photomasks. It offers flexible and convenient applications with a wide range of uses. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic flowchart of the ZnO micro / nano particle patterning method provided in the embodiments of this application;

[0032] Figure 2 This is a schematic diagram of an ultraviolet light irradiation process provided in an embodiment of this application;

[0033] Figure 3 This is a schematic diagram of the ZnO micro / nano particle patterning method provided in Embodiment 1 of this application;

[0034] Figure 4 This is an overall morphological image of the patterned ZnO thin film provided in Embodiment 1 of this application;

[0035] Figure 5 This is a top microscopic view of the patterned ZnO thin film provided in Embodiment 1 of this application;

[0036] Figure 6This is a SEM image of the patterned ZnO thin film provided in Embodiment 1 of this application at a resolution of 10 μm.

[0037] Figure 7 This is a SEM image of the patterned ZnO thin film provided in Embodiment 1 of this application at a resolution of 1 μm.

[0038] Figure 8 This is a ZnO thin film image with a butterfly pattern provided in Embodiment 2 of this application;

[0039] Figure 9 This is a morphology diagram of the patterned ZnO thin film provided in Embodiment 3 of this application. Figure 9 Image A in the image is a digital photograph of a patterned ZnO thin film. Figure 9 Image B in the image is a scanning electron microscope (SEM) image of a portion of the patterned ZnO thin film. Figure 9 Figure C in the image shows a SEM image of the patterned ZnO thin film under a microscopic view. Detailed Implementation

[0040] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0041] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0042] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0043] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0044] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0045] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass mentioned in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0046] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0047] The term "UV" is an abbreviation for "Ultraviolet," which refers to ultraviolet radiation. It is a general term for radiation in the electromagnetic spectrum with frequencies ranging from 750 THz to 30 PHz, corresponding to wavelengths of 400 nm to 10 nm in a vacuum, and cannot be perceived by humans.

[0048] As attached Figure 1 As shown, the first aspect of this application provides a method for patterning ZnO micro / nanoparticles, comprising the following steps:

[0049] S10. Preparation of ZnO micro / nanoparticles with positive surface charge;

[0050] S20. Negatively charged groups are grafted onto the surface of ZnO micro / nano particles to obtain a dispersion of modified ZnO particles;

[0051] S30. Obtain a substrate with a negatively charged surface, and form a wet film of the dispersion on the substrate with a negatively charged surface;

[0052] S40. The wet film is subjected to ultraviolet light irradiation through a photomask to obtain a patterned ZnO film.

[0053] The ZnO micro / nanoparticle patterning method provided in the first aspect of this application involves grafting negatively charged groups onto the surface of positively charged ZnO micro / nanoparticles, thus making the surface negatively charged. A dispersion of the modified ZnO particles is deposited on a negatively charged substrate to form a wet film. The wet film is then locally irradiated with ultraviolet light using a mask. Under the influence of ultraviolet light, the negatively charged groups on the surface of the ZnO micro / nanoparticles are decomposed in the irradiated area, causing the surface potential of the ZnO micro / nanoparticles to return to positive charge, making them easily deposited on the negatively charged substrate surface through electrostatic adsorption. Furthermore, the ZnO micro / nanoparticles themselves readily undergo photocorrosion under ultraviolet light irradiation, continuously releasing zinc ions during the irradiation process. These zinc ions serve as bonding sites. Bonds are formed between the negatively charged groups and the zinc ions, thereby inducing bonding between the modified ZnO particles. Therefore, through the combined effects of electrostatic adsorption and the bonding force between negatively charged groups and zinc ions, the ZnO micro / nanoparticles in the UV-irradiated areas are stably bonded to the electronegative substrate. In the areas shielded by the mask and not irradiated by UV light, electrostatic repulsion exists between the electronegative ZnO micro / nanoparticles and the electronegative substrate, allowing the ZnO micro / nanoparticles to be easily removed from the substrate surface, thus forming a patterned ZnO film on the substrate surface. Furthermore, the ZnO micro / nanoparticle patterning method in this application uses ZnO micro / nanoparticles that are already crystalline, eliminating the need for subsequent annealing. UV patterning is applicable not only to high-temperature resistant rigid substrates such as glass but also to low-temperature resistant flexible substrates such as PVC. It eliminates the need for photoresist, is simple to operate, has no special requirements for the operating environment, and offers mild preparation conditions at a low cost. Different patterned ZnO films can be obtained by adjusting the mask pattern, and due to the high efficiency of UV irradiation, large-area patterned ZnO films can be rapidly prepared.

[0054] In some possible implementations, the method for preparing positively charged ZnO micro / nanoparticles in step S10 above includes: obtaining positively charged ZnO micro / nanoparticles by thermally decomposing zinc oxide precursor materials.

[0055] In some possible implementations, the method for preparing ZnO micro / nanoparticles with positively charged surfaces includes the following steps: dissolving raw materials such as Zn(OAC)2 in a solvent such as diethylene glycol, stirring thoroughly to obtain a homogeneous solution; then subjecting the homogeneous solution to a hydrothermal reaction at 100–200°C for 1–3 hours, followed by natural cooling; centrifuging the cooled solution and retaining the supernatant as a seed layer solution; preparing a Zn(OAC)2 solution again, raising the temperature of the solution from room temperature to 100–200°C, maintaining it for 10–30 minutes, removing it, adding the above seed layer solution and mixing thoroughly, then placing it back into an oven at 150–200°C for 3–8 hours, followed by natural cooling. The cooled solution was centrifuged, and the ZnO micro-nano particles were cleaned with deionized water and dried. After the ZnO micro-nano particles were completely dried, they were subjected to heat annealing in air at 200-400℃ for 1-3 hours to obtain ZnO micro-nano particles with positive surface charge.

[0056] In some possible implementations, the method for preparing positively charged ZnO micro / nanoparticles includes the following steps: adding a zinc source such as Zn(NO3)2·6H2O and a complexing agent such as hexamethylenetetramine to deionized water, mixing thoroughly, then adding a flocculant such as sodium citrate dihydrate and mixing thoroughly; then heating the mixed solution to 70–100°C for 30–60 min, removing it, and allowing it to cool naturally; centrifuging the solution, washing the particulate product with deionized water, and drying it; after the particulate product is completely dry, performing a heat annealing treatment in air at 300–500°C for 1–3 h to obtain positively charged ZnO micro / nanoparticles.

[0057] In some possible implementations, the average particle size of ZnO micro / nanoparticles is 100 nm to 4 μm. Under this particle size condition, ZnO micro / nanoparticles are more likely to be stably deposited on the substrate to form a ZnO thin film, reducing the influence of the ZnO micro / nanoparticles' own gravity on the stability of the ZnO thin film deposition. It also facilitates the deposition of ZnO micro / nanoparticles on the substrate, preventing them from easily suspending or detaching and making it difficult to form a patterned ZnO thin film. Furthermore, since the ZnO micro / nanoparticles are already crystalline, no further annealing is required. Ultraviolet patterning is suitable not only for rigid substrates resistant to high temperatures, such as glass, but also for flexible substrates that are not resistant to high temperatures, such as PVC. In some specific embodiments, the average particle size of the ZnO micro / nanoparticles can be 100 nm to 500 nm, 50 nm to 1 μm, 1 to 2 μm, 2 to 3 μm, 3 to 4 μm, etc.

[0058] In some possible implementations, step S20 above, the method of grafting negatively charged groups onto the surface of ZnO micro / nano particles, includes: mixing ZnO micro / nano particles with negatively charged organic compounds in a solvent, causing the negatively charged groups in the organic compounds to be grafted onto the surface of the ZnO micro / nano particles, followed by separation and washing to obtain a dispersion of modified ZnO particles. In some specific embodiments, after mixing, the mixture is centrifuged and washed multiple times with deionized water to remove unreacted organic raw materials and impurities such as free byproducts generated in the mixed solution.

[0059] In some specific embodiments, ZnO micro / nanoparticles are ultrasonically dispersed in deionized water to form a uniform and stable solution. Then, an organic compound with negatively charged groups is added and stirred for 12–36 hours to allow the negatively charged groups in the organic compound to fully bind to the surface of the ZnO micro / nanoparticles. After the reaction, the solution is centrifuged and washed multiple times with deionized water to remove unreacted organic raw materials and impurities such as free by-products generated in the mixed solution, thus obtaining a dispersion of modified ZnO particles.

[0060] In some possible implementations, the negatively charged groups include carboxyl groups (-COOH) and carboxylate groups (-COO). - ), sulfonic acid group (-SO3H), sulfonate group (-SO3) - The grafted groups are at least one of the following: ), , and ; these organic groups all carry a negative charge and readily combine with the positively charged surface of ZnO micro / nano particles through electrostatic forces. After grafting onto the surface of ZnO micro / nano particles, the originally positively charged surface potential of the ZnO micro / nano particles is converted to a negative charge, thus exhibiting electronegativity. Furthermore, after these negatively charged groups are grafted onto the surface of ZnO micro / nano particles, under ultraviolet light irradiation, these negatively charged groups easily decompose and detach from the surface of the ZnO micro / nano particles, thereby causing the surface potential of the ZnO micro / nano particles to return to positive.

[0061] In some possible implementations, the mass ratio of ZnO micro / nanoparticles to organic matter is 1:(0.1–0.3). In this case, the negatively charged groups in the organic matter of this mass ratio can be sufficiently modified onto the surface of the ZnO micro / nanoparticles, causing the surface of the ZnO micro / nanoparticles to change from being positively charged to negatively charged, resulting in electronegativity on the modified ZnO particle surface. In some specific embodiments, the mass ratio of ZnO micro / nanoparticles to organic matter can be 1:(0.1–0.15), 1:(0.15–0.2), 1:(0.2–0.25), 1:(0.25–0.3), etc.

[0062] In some possible implementations, the organic compound includes at least one of sodium citrate and potassium citrate. These organic compounds contain a carboxylic acid group (-COOH) or a carboxylate group (-COO). - By mixing these organic compounds with ZnO micro / nanoparticles in a solvent, the surface of the modified ZnO particles can be grafted with at least one negatively charged group, either a carboxylic acid group (-COOH) or a carboxylate group (-COO-).

[0063] In some specific embodiments, the surface of the modified ZnO particles is grafted with carboxylic acid groups (-COOH) and carboxylate groups (-COO). - At least one of the following: In the embodiments of this application, the surface of the modified ZnO particles is grafted with carboxylic acid groups (-COOH) and carboxylate groups (-COO). - It exhibits electronegativity, and upon subsequent ultraviolet irradiation, the ultraviolet light can decompose the carboxylic acid groups (-COOH) and carboxylate groups (-COO) grafted on the surface of the modified ZnO particles. - This process causes the surface potential of ZnO micro / nano particles to become positive, leading to their deposition on the substrate surface via electrostatic adsorption, forming an electrostatically adsorbed ZnO micro / nano particle layer. Furthermore, ZnO itself is readily photo-corroded under ultraviolet light, continuously releasing zinc ions during illumination. This triggers the formation of COO-Zn bonds between carboxyl functional groups and zinc ions. Through these COO-Zn bonds, modified ZnO particles near the electrostatically adsorbed ZnO micro / nano particle layer can be bound to its surface. Based on these two effects induced by ultraviolet light, patterned ZnO thin films can be obtained on a negatively charged substrate.

[0064] In some possible implementations, the concentration of the dispersion is 10–40 mg / mL; specifically, the concentration can be 10–20 mg / mL, 20–30 mg / mL, 30–40 mg / mL, etc. In the embodiments of this application, a dispersion within this concentration range not only facilitates the formation of a wet film on a negatively charged substrate and promotes stable wet film formation, but also facilitates the formation of a patterned ZnO thin film with uniform thickness, a smooth surface, and a dense film after subsequent ultraviolet irradiation treatment.

[0065] In some possible implementations, the method for obtaining a substrate with a negatively charged surface in step S30 above includes: after obtaining the substrate, subjecting the substrate to plasma treatment to obtain a substrate with a negatively charged surface. This application achieves this by subjecting the substrate surface to plasma treatment, thereby modifying the substrate surface with certain physicochemical properties, resulting in a negatively charged surface. This also improves surface adhesion.

[0066] In some possible implementations, the negatively charged substrate includes at least one of glass substrate, silicon substrate, and polyvinyl chloride (PVC). The surfaces of these substrates are all negatively charged. After the modified ZnO particles are treated with ultraviolet light, the negatively charged groups grafted onto their surfaces decompose and fall off, and the ZnO micro / nano particles, whose surface potential returns to positive, can stably bond with the negatively charged substrate through electrostatic adsorption. In the embodiments of this application, the negatively charged substrate can be either a transparent or opaque substrate, a rigid or flexible substrate, or a high-temperature resistant or low-temperature resistant substrate. In some specific embodiments, the zeta potential of the glass substrate surface is approximately -66mV.

[0067] In some possible implementations, the average thickness of the wet film is 150–200 μm. In this case, depositing a wet film of this thickness is beneficial for forming a patterned ZnO thin film with uniform thickness and a dense, flat surface after subsequent ultraviolet irradiation treatment. In some specific embodiments, the average thickness of the wet film can be 150–160 μm, 160–170 μm, 170–180 μm, 180–190 μm, 190–200 μm, etc.

[0068] In some possible implementations, in step S40 above, the wet film is subjected to ultraviolet (UV) irradiation using a mask. The UV irradiation conditions include irradiation for 10–30 seconds at a UV wavelength of 100–365 nm. Under these conditions, the negatively charged groups grafted onto the surface of the modified ZnO particles decompose and detach, causing the surface potential of the ZnO micro / nano particles to return to positive charge. This allows them to stably bond with the negatively charged substrate through electrostatic adsorption. Furthermore, the ZnO micro / nano particles themselves readily undergo photocorrosion under UV irradiation, continuously releasing zinc ions during the process. These zinc ions act as bonding sites, forming bonds between the negatively charged groups and the zinc ions, which in turn induces bonding between the modified ZnO particles. This allows the ZnO micro / nano particles to further deposit on the substrate, forming a patterned ZnO thin film.

[0069] In some specific embodiments, the substrate with a negatively charged surface can be either a transparent substrate or an opaque substrate. When the substrate is opaque, a photomask is placed above the wet film, and ultraviolet light passes through the photomask to irradiate the wet film, thus performing ultraviolet irradiation treatment. Zinc oxide particles in the areas of the wet film irradiated by the ultraviolet light transmitted through the photomask are fixed onto the substrate, forming a patterned ZnO thin film. When the substrate is transparent, the photomask can be placed directly below the transparent substrate, and ultraviolet light passes through the photomask to irradiate the wet film, thus performing ultraviolet irradiation treatment. Zinc oxide particles in the areas of the wet film irradiated by the ultraviolet light transmitted through the photomask are fixed onto the substrate, forming a patterned ZnO thin film. A schematic diagram is attached. Figure 2 As shown.

[0070] Secondly, embodiments of this application provide a patterned ZnO film, which is prepared according to the above method. The surface of the patterned ZnO film close to the substrate is bonded to the substrate by electrostatic adsorption, while the surface away from the substrate is bonded by zinc ion bonding sites.

[0071] The patterned ZnO film provided in this embodiment is prepared by the above method. Originally positively charged ZnO micro / nano particles are modified with negatively charged groups. Under ultraviolet light irradiation, these negatively charged groups decompose, causing the surface potential of the ZnO micro / nano particles to return to positive charge. They then bind to the negatively charged substrate surface through electrostatic adsorption. Furthermore, during ultraviolet light irradiation, the ZnO micro / nano particles undergo photocorrosion, continuously releasing zinc ions. Bonds are formed between the negatively charged groups and zinc ions, which act as bonding sites. These zinc ions then move away from the substrate surface, causing the modified ZnO particles to bond together through these zinc ion bonding sites, forming a film layer. Therefore, the patterned ZnO film formed in this embodiment, through the combined effects of electrostatic adsorption and zinc ion bonding sites, exhibits good film stability, uniformity, and flatness. Moreover, the pattern, thickness, and area of ​​the patterned ZnO film can be flexibly adjusted to meet different application requirements.

[0072] In some possible implementations, the average thickness of the patterned ZnO film is 100 nm to 20 μm. Specifically, the average thickness of the patterned ZnO film can be 100–500 nm, 500–1000 nm, 1–3 μm, 3–5 μm, 5–8 μm, 8–10 μm, 10–13 μm, 13–15 μm, 15–18 μm, 18–20 μm, etc. In the embodiments of this application, the thickness of the patterned ZnO film can be flexibly controlled by adjusting the duration of the ultraviolet irradiation process and the concentration of the dispersion, thus obtaining patterned ZnO films of different thicknesses, providing flexibility and convenience in application. Furthermore, the pattern and area size of the patterned ZnO film can also be flexibly controlled to meet different application requirements.

[0073] Thirdly, embodiments of this application provide an application of the above-mentioned patterned ZnO film, applying the patterned ZnO film to at least one of the fields of UV photodetectors, gas sensors, and ultraviolet light absorption plates.

[0074] The patterned ZnO film provided in this application can be used to fabricate devices such as UV photodetectors and gas sensors because zinc oxide exhibits a rapid photocurrent response under UV light irradiation. Furthermore, since zinc oxide absorbs ultraviolet light, the patterned ZnO film can be applied to ultraviolet light absorbing plates such as photomasks. It offers flexible and convenient applications with a wide range of uses.

[0075] To enable those skilled in the art to clearly understand the above-described implementation details and operations, and to demonstrate the significant improvement in the performance of the ZnO micro / nanoparticle patterning method in the embodiments of this application, the following examples illustrate the above technical solutions.

[0076] Example 1

[0077] A patterned ZnO thin film includes the following steps, as illustrated in the attached diagram. Figure 3 As shown:

[0078] ① The synthesis of ZnO micro / nanoparticles with a diameter of approximately 400 nm involved the following steps: 1.8348 g of Zn(OAC)₂ was dissolved in 100 mL of diethylene glycol and stirred for at least 8 hours; the mixture was then heated in an oven to 160°C for 1 hour, removed, and allowed to cool naturally; the cooled solution was centrifuged at high speed (10,000 rpm for 10 minutes), and the supernatant was retained as the seed layer solution; 1.8348 g of Zn(OAC)₂ was again dissolved in 100 mL of diethylene glycol (DEG) and stirred for at least 8 hours; the solution was then placed in an oven, and the oven temperature was increased from room temperature to 150°C. After holding for 20 minutes, remove the sample and add 200 μL of seed layer solution. Stir for 5 minutes and then place it back into the oven. Raise the oven temperature to 170°C and hold for 5 hours. Remove the sample and allow it to cool naturally. Centrifuge the cooled solution at 10,000 rpm for 5 minutes to collect the solution. Clean the ZnO micro / nanoparticles with deionized water and dry them in a 60°C oven. After the ZnO micro / nanoparticles are completely dry, place them in a muffle furnace and anneal them in air at 300°C for 1 hour to obtain submicron ZnO micro / nanoparticles with a diameter of approximately 400 nm and a positively charged surface.

[0079] ② Weigh 400 mg of submicron ZnO micro / nano particles and ultrasonically disperse them in 40 mL of deionized water; weigh 4 g of sodium citrate and add it to the solution, stirring for 24 h; centrifuge the mixed solution three times with deionized water to remove free sodium citrate from the solution, and obtain a dispersion of modified ZnO particles.

[0080] ③ Clean the ordinary glass slide with anhydrous ethanol and deionized water in sequence using ultrasonic cleaning, dry it with a hair dryer or dry it in a 60℃ oven, and treat the cleaned and dried glass substrate with a plasma cleaner for 90 seconds to obtain a glass slide with a negative surface charge.

[0081] ④ The dispersion of modified ZnO particles treated with sodium citrate was dropped onto a glass slide with a negatively charged surface. A photomask was placed directly below the glass slide, and ultraviolet light with a wavelength of 365nm was irradiated onto the dispersion on the glass slide through the photomask for 20 seconds. Then, the slide was gently rinsed with water to obtain a patterned ZnO thin film on the glass substrate.

[0082] Example 2

[0083] A patterned ZnO thin film is prepared in the same way as in Example 1, except that: in step ③, polyvinyl chloride (PVC) is used as the substrate; and in step ④, the photomask pattern is a butterfly pattern, resulting in a butterfly-patterned ZnO thin film on the PVC substrate.

[0084] Example 2

[0085] A patterned ZnO thin film includes the following steps:

[0086] ① The synthesis of ZnO micro / nanoparticles with a diameter of approximately 4 μm involved the following steps: 1.48745 g of Zn(NO3)2·6H2O and 0.70093 g of hexamethylenetetramine were weighed and added to 150 mL of deionized water. After stirring for 20 min, 0.55879 g of sodium citrate dihydrate was added, and stirring was continued for another 10 min. The mixed solution was then placed in an oven and heated to 90 °C for 40 min. After that, it was removed and allowed to cool naturally for 1 h. The solution was collected by centrifugation (2000 rpm, 2 min). The ZnO micro / nanoparticles were washed three times with deionized water and then dried in a 60 °C oven. After the ZnO micro / nanoparticles were completely dried, they were placed in a muffle furnace and annealed in air at 500 °C for 1 h to obtain micron-sized ZnO micro / nanoparticles with a diameter of approximately 4 μm and a positively charged surface.

[0087] ② Weigh 400 mg of micron-sized ZnO micro / nano particles and ultrasonically disperse them in 40 mL of deionized water; weigh 4 g of sodium citrate and add it to the solution, and stir for 24 h; centrifuge the mixed solution three times with deionized water to remove free sodium citrate from the solution, and obtain a dispersion of modified ZnO particles.

[0088] ③ Clean the ordinary glass slide with anhydrous ethanol and deionized water in sequence using ultrasonic cleaning, dry it with a hair dryer or dry it in a 60℃ oven, and treat the cleaned and dried glass substrate with a plasma cleaner for 90 seconds to obtain a glass slide with a negative surface charge.

[0089] ④ The dispersion of modified ZnO particles treated with sodium citrate was dropped onto a glass slide with a negatively charged surface. A photomask was placed directly below the glass slide, and ultraviolet light with a wavelength of 365nm was irradiated onto the dispersion on the glass slide through the photomask for 20 seconds. Then, the slide was gently rinsed with water to obtain a patterned ZnO thin film on the glass substrate.

[0090] Furthermore, to verify the progressiveness of the embodiments of this application, the patterned ZnO thin films prepared in the above embodiments were subjected to the following tests:

[0091] 1. The morphology of the patterned ZnO thin film prepared in Example 1 was observed by scanning electron microscopy (SEM), as shown in the attached figure. Figures 4 to 7 As shown, among which, appendix Figure 4 The image shows the overall morphology of the patterned ZnO thin film, revealing that ZnO micro / nano particles have formed a stable pattern on the glass substrate. Figure 5 This is a top-microscopic view of a patterned ZnO thin film, showing that the ZnO micro / nano particles in the film have high uniformity in size and are evenly distributed. (Attached) Figure 6 and attached Figure 7 The images show cross-sectional test images of the patterned ZnO thin film at different resolutions, revealing that the fabricated patterned ZnO thin film is uniform, flat, and dense.

[0092] 2. The butterfly-patterned ZnO thin film prepared on a PVC substrate in Example 2 was observed, as shown in the attached figure. Figure 8 As shown, the butterfly pattern of the ZnO thin film is clearly visible and can be bent along with the PVC substrate.

[0093] 3. The morphology of the patterned ZnO thin film prepared in Example 3 was observed, as shown in the attached figure. Figure 9 As shown, among which, appendix Figure 9 Image A is a digital photograph of a patterned ZnO thin film. The patterned ZnO film's design is clearly the logo of Southern University of Science and Technology. (Attached) Figure 9 Image B in the image shows a partial scanning electron microscope (SEM) image of the patterned ZnO thin film. The SEM image clearly shows a clear and complete pattern of ZnO micro / nano particles. (Attached) Figure 9 Figure C shows the SEM observation of the patterned ZnO film under a microscopic view. It can be seen that the ZnO micro and nano particles in the patterned ZnO film have a high uniformity in particle size and are evenly distributed.

[0094] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for patterning ZnO micro / nanoparticles, characterized in that, Includes the following steps: Preparation of ZnO micro / nanoparticles with positive surface charge; Negatively charged groups were grafted onto the surface of the ZnO micro / nano particles to obtain a dispersion of modified ZnO particles. Obtain a substrate with a negatively charged surface, and form a wet film of the dispersion on the substrate with a negatively charged surface; A patterned ZnO film is obtained by irradiating the wet film with ultraviolet light using a photomask.

2. The ZnO micro / nanoparticle patterning method as described in claim 1, characterized in that, The method for preparing ZnO micro / nanoparticles with positive surface charge includes: obtaining the ZnO micro / nanoparticles with positive surface charge by thermally decomposing zinc oxide precursor material. And / or, the method of grafting the negatively charged groups onto the surface of the ZnO micro / nanoparticles includes: mixing the ZnO micro / nanoparticles with an organic compound carrying negatively charged groups in a solvent, separating and washing them to obtain a dispersion of the modified ZnO particles; And / or, the conditions for the ultraviolet irradiation treatment include: irradiation for 10 to 30 seconds under ultraviolet light wavelengths of 100 to 365 nm.

3. The ZnO micro / nanoparticle patterning method as described in claim 1 or 2, characterized in that, The average particle size of the ZnO micro / nano particles is 100 nm to 4 μm.

4. The ZnO micro / nanoparticle patterning method as described in claim 2, characterized in that, The negatively charged group includes at least one of carboxylic acid group, carboxylate group, sulfonic acid group, sulfonate group, and alkyd group; And / or, the mass ratio of the ZnO micro / nanoparticles to the organic matter is 1:(0.1-0.3).

5. The ZnO micro / nanoparticle patterning method as described in claim 4, characterized in that, The surface of the modified ZnO particles is grafted with at least one of carboxylic acid groups and carboxylate groups. And / or, the organic compound includes at least one of sodium citrate and potassium citrate.

6. The method for patterning ZnO micro / nanoparticles as described in any one of claims 2, 4, or 5, characterized in that, The substrate with a negatively charged surface includes at least one of glass substrate, silicon substrate, and polyvinyl chloride; And / or, the method for obtaining a substrate with a negatively charged surface includes: after obtaining the substrate, performing plasma treatment on the substrate to obtain the substrate with a negatively charged surface.

7. The ZnO micro / nanoparticle patterning method as described in claim 6, characterized in that, The concentration of the dispersion is 10–40 mg / mL; And / or, the average thickness of the wet film is 150–200 μm.

8. A patterned ZnO film, characterized in that, The patterned ZnO film is prepared according to the method described in any one of claims 1 to 7. The surface of the patterned ZnO film close to the substrate is bonded to the substrate by electrostatic adsorption, and the surface away from the substrate is bonded by zinc ion bonding sites.

9. The patterned ZnO film as described in claim 8, characterized in that, The average thickness of the patterned ZnO film is 100 nm to 20 μm.

10. An application of the patterned ZnO film as described in any one of claims 8 to 9, characterized in that, The patterned ZnO film is applied to at least one of the following fields: UV photodetectors, gas sensors, and ultraviolet light absorption plates.

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