Preparation method and application of a complex-phase CsBr / Cs3Bi2Br3I6 array film

Abstract

The application discloses a preparation method of a complex-phase CsBr / Cs3Bi2Br3I6 array film and application thereof, and relates to the technical field of semiconductors.The specific process of the application is as follows: CsBr microspheres are deposited on the surface of interdigital electrodes by a simple gas phase evaporation method of cesium bromide, bismuth iodide is used as a reaction raw material, N,N-dimethylformamide is used as a solvent, and a Cs3Bi2Br3I6 array film is in-situ reaction-grown on the CsBr microspheres by multiple spraying and heat treatment, the film is uniform and porous, Cs3Bi2Br3I6 sheet-shaped nanocrystals are vertically grown on the surface and gaps of the CsBr microspheres, the diameter of the CsBr microspheres is 1-3 microns, the thickness of the Cs3Bi2Br3I6 nanosheet is 50-100 nanometers, the film is firmly combined with a base material, and the prepared complex-phase CsBr / Cs3Bi2Br3I6 array film shows room-temperature sensitive performance to hydrogen sulfide gas.Compared with the prior art, the application has the advantages of reasonable preparation process design, high uniformity of large-area film formation, strong operability, high sensitivity to H2S gas at room temperature, and good long-term stability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to a method for preparing a multiphase CsBr / Cs3Bi2Br3I6 array thin film and its application. Background Technology

[0002] With the increasing deterioration of the ecological environment and the growing demand for biomonitoring, there is an urgent need for efficient and real-time monitoring of trace gases. While gas sensors are widely used to detect various toxic, harmful, explosive, and volatile substances, traditional semiconductor gas sensors on the market generally require operating temperatures, have high power consumption, and pose certain dangers for some flammable and explosive gases. As gas sensors continue to develop towards thin-film, nano-scale, and array-based designs, room temperature detection has become a prerequisite for achieving thin-film and array-based development. Currently, all-inorganic halide perovskite thin films are widely studied in fields such as solar cells, photoelectric sensors, and gas / humidity sensors due to their excellent photoelectric properties and thermal stability. Their preparation technology mainly involves a single-phase liquid-phase spin-coating method. However, as a gas sensor, during the spin-coating process on the interdigitated electrode surface, the low solubility of CsBr in N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) results in low film thickness and poor film uniformity, leading to unstable gas-sensing response performance and hindering large-scale industrial production. New methods for depositing metal halide Cs3Bi2Br3I6 thin films urgently need to be developed to solve the above problems. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the above-mentioned technical problems and provide a method for preparing a multiphase CsBr / Cs3Bi2Br3I6 array thin film with reasonable preparation process design, high uniformity of large-area film formation, strong operability, high sensitivity to H2S gas at room temperature, and good long-term stability, as well as its application.

[0004] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a method for preparing a multiphase CsBr / Cs3Bi2Br3I6 array thin film, comprising the following steps:

[0005] S1: CsBr microspheres were deposited on the surface of the interdigitated electrode using a simple cesium bromide vapor deposition method;

[0006] S2: Using bismuth iodide as the reactant and N,N-dimethylformamide as the solvent, a bismuth iodide solution was prepared, and a Cs3Bi2Br3I6 array film was grown in situ on CsBr microspheres through multiple spraying and heat treatment.

[0007] S3: Cs3Bi2Br3I6 sheet-like nanocrystals grow vertically on the surface and in the gaps of CsBr microspheres. The diameter of the CsBr microspheres is 1-3 micrometers, and the thickness of the Cs3Bi2Br3I6 nanosheets is 50-100 nanometers. They are firmly bonded to the substrate material.

[0008] As an improvement, the linewidth and spacing of the interdigitated electrodes are both 20-30 micrometers.

[0009] As an improvement, the interdigitated electrodes in S1 are ultrasonically cleaned with acetone and ethanol before use, and then dried for later use.

[0010] As an improvement, the simple vapor deposition method in S1 involves placing a certain amount of cesium bromide powder in a quartz tube with a diameter of 1 cm and a height of 5 cm, suspending interdigitated electrodes 1-2 cm above the powder, ensuring that the surface of the interdigitated electrodes faces downward and is parallel to the powder surface, controlling the bottom temperature of the quartz tube to 700-900℃ using a heating furnace, heating to evaporate the cesium bromide and deposit it on the surface of the interdigitated electrodes above it, controlling the evaporation time to 20-30 minutes, and obtaining a CsBr microsphere layer.

[0011] As an improvement, the preparation process of the bismuth iodide solution in S2 is as follows: dissolve bismuth iodide in N,N-dimethylformamide solution, and stir magnetically for 20-30 minutes to ensure complete dissolution, thereby obtaining a bismuth iodide solution with a molar concentration of 20 mmol / L.

[0012] As an improvement, the steps of the spraying method in S2 are as follows: 200 μL of bismuth iodide solution is placed in an electric airbrush with a nozzle diameter of 0.3 mm; the interdigitated electrode with the CsBr microsphere layer is preheated to 110°C, and then the nozzle is vertically aligned with the center of the interdigitated electrode. Spraying is performed 5-10 times at a distance of 5 cm from its surface. Then the interdigitated electrode is placed in a drying oven and heated at 115-125°C for 20-40 minutes to obtain a multiphase Cs3Bi2Br3I6 array film.

[0013] An application of a multiphase CsBr / Cs3Bi2Br3I6 array thin film involves mounting the multiphase CsBr / Cs3Bi2Br3I6 array thin film prepared by the above method onto the fixed pins of the electrode to obtain a thin-film type multiphase CsBr / Cs3Bi2Br3I6 room temperature H2S gas sensor.

[0014] With the above structure, the present invention has the following advantages:

[0015] This invention uses a simple vapor phase evaporation method to directly prepare CsBr microspheres, which makes the size of the CsBr microspheres controllable, highly operable, and reproducible. The preparation process is simple and suitable for large-scale industrial production.

[0016] This invention utilizes an in-situ reaction method to achieve the application of multiphase CsBr / Cs3Bi2Br3I6 array thin film for hydrogen sulfide gas detection and leakage alarm at room temperature. It offers high safety and is suitable for array applications of gas sensors.

[0017] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0018] Figure 1 This is a SEM image of the CsBr / Cs3Bi2Br3I6 array thin film obtained in Example 1 of the preparation method of the multiphase CsBr / Cs3Bi2Br3I6 array thin film of the present invention.

[0019] Figure 2 This is the XRD pattern of the CsBr / Cs3Bi2Br3I6 array thin film obtained in Example 1 of the preparation method of the multiphase CsBr / Cs3Bi2Br3I6 array thin film of the present invention.

[0020] Figure 3 This is a room temperature resistance response recovery curve of the CsBr / Cs3Bi2Br3I6 array thin film gas sensor obtained in Example 2 of the preparation method of the multiphase CsBr / Cs3Bi2Br3I6 array thin film of the present invention to 1 ppm hydrogen sulfide gas.

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Implementation

[0022] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0023] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] Combination Figures 1-3A simple vapor-phase deposition method evaporates and deposits cesium bromide into a film at temperatures of 700-900℃. By controlling the heating temperature, the position of the interdigitated electrodes, and the deposition time, the thickness and size of the CsBr microsphere layer can be controlled. Moreover, the film formed by the simple vapor-phase deposition method adheres firmly to the surface of the interdigitated electrodes, effectively reducing the lattice mismatch between the subsequent sheet-like Cs3Bi2Br3I6 array and the surface of the interdigitated electrodes. Bismuth iodide solution was sprayed onto the surface of CsBr microspheres, and Cs3Bi2Br3I6 plate-like crystals were prepared by in-situ reaction of BiI3 with CsBr microspheres to obtain a surface highly sensitive to hydrogen sulfide. At the same time, the formation of CsBr / Cs3Bi2Br3I6 heterojunction also facilitates the preparation of a surface highly sensitive to hydrogen sulfide. The gas sensor prepared by the above method can achieve a sensitivity of more than 1.5 to 10 ppm hydrogen sulfide gas at room temperature, with a response time of less than 15 seconds. Under the same test conditions, the gas sensor showed very low responsiveness to 100 ppm ethanol, formaldehyde, ammonia, and methane gas. Therefore, the gas sensor has high selectivity for hydrogen sulfide gas. Example

[0025] 20 mg of cesium bromide was placed at the bottom of a quartz tube with a diameter of 1 cm and a height of 5 cm. An interdigitated electrode was suspended 1.3 cm above the powder, ensuring the electrode surface was downward and parallel to the powder surface. The temperature at the bottom of the quartz tube was controlled at 900 °C using a heating furnace, and the evaporation time was controlled at 25 minutes to obtain gaseous CsBr, which was then condensed onto a substrate to obtain a CsBr microsphere layer. Next, 65 mg of BiI3 was dissolved in 5.5 mL of N,N-dimethylformamide to prepare a bismuth iodide solution. 200 μL of the BiI3 solution was added to the spray bottle of an electric airbrush using a pipette and sprayed onto the preheated CsBr film surface in 7 coats. The film was then annealed at 115 °C for 40 minutes to obtain a CsBr / Cs3Bi2I6Br3 film. A CsBr / Cs3Bi2I6Br3 thin film was mounted on the fixed pin of the electrode to obtain a thin film-type CsBr / Cs3Bi2I6Br3 room temperature H2S gas detection gas sensor. The gas sensitivity test results show that its sensitivity to 10 ppm hydrogen sulfide gas at room temperature is 1.9, the response time is less than 15 s, and the lowest detection concentration can reach 500 ppb. Example

[0026] Based on Example 1, the bottom temperature of the quartz tube was changed to 700℃, the interdigitated electrode was suspended 1 cm above the powder, the evaporation time was changed to 30 minutes, and other preparation processes remained unchanged. The resulting CsBr / Cs3Bi2I6Br3 thin film gas sensor had a sensitivity of more than 1.5 to 1 ppm hydrogen sulfide gas at room temperature, a response time of 10 s, and high selectivity to hydrogen sulfide gas. Example

[0027] Based on Example 1, the number of spraying passes onto the preheated CsBr film surface was changed to 10. Subsequently, annealing was performed at 125°C for 20 minutes to obtain a CsBr / Cs3Bi2I6Br3 film. Other preparation processes remained unchanged. The resulting CsBr / Cs3Bi2I6Br3 film gas sensor exhibited a sensitivity of 1.2 to 500 ppb hydrogen sulfide gas at room temperature, a response time of less than 10 s, and high selectivity for hydrogen sulfide gas.

[0028] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. Actual embodiments are not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for preparing a multiphase CsBr / Cs3Bi2Br3I6 array thin film, characterized in that: Includes the following steps: S1: CsBr microspheres were deposited on the surface of the interdigitated electrode using a simple cesium bromide vapor deposition method; S2: Using bismuth iodide as the reactant and N,N-dimethylformamide as the solvent, a bismuth iodide solution was prepared, and a Cs3Bi2Br3I6 array film was grown in situ on CsBr microspheres through multiple spraying and heat treatment. S3: Cs3Bi2Br3I6 sheet-like nanocrystals grow vertically on the surface and in the gaps of CsBr microspheres. The diameter of the CsBr microspheres is 1-3 micrometers, and the thickness of the Cs3Bi2Br3I6 nanosheets is 50-100 nanometers. They are firmly bonded to the substrate material.

2. The method for preparing a multiphase CsBr / Cs3Bi2Br3I6 array thin film according to claim 1, characterized in that: The interdigitated electrodes in S1 are silicon-based electrodes or ceramic-based electrodes, and the linewidth and line spacing of the interdigitated electrodes are both 20-30 micrometers.

3. The method for preparing a multiphase CsBr / Cs3Bi2Br3I6 array thin film according to claim 1, characterized in that: Before use, the interdigitated electrodes in S1 are ultrasonically cleaned with acetone and ethanol, and then dried for later use.

4. The method for preparing a multiphase CsBr / Cs3Bi2Br3I6 array thin film according to claim 1, characterized in that: The simple vapor deposition method in S1 involves placing a certain amount of cesium bromide powder in a quartz tube with a diameter of 1 cm and a height of 5 cm. An interdigitated electrode is suspended 1-2 cm above the powder, ensuring that the surface of the interdigitated electrode faces downward and is parallel to the powder surface. The temperature of the bottom of the quartz tube is controlled at 700-900℃ using a heating furnace. The cesium bromide is evaporated by heating and deposited on the surface of the interdigitated electrode above it. The evaporation time is controlled at 20-30 minutes to obtain a CsBr microsphere layer.

5. The method for preparing a multiphase CsBr / Cs3Bi2Br3I6 array thin film according to claim 1, characterized in that: The preparation process of the bismuth iodide solution in S2 is as follows: dissolve bismuth iodide in N,N-dimethylformamide solution, and stir magnetically for 20-30 minutes to ensure complete dissolution, thereby obtaining a bismuth iodide solution with a molar concentration of 20 mmol / L.

6. The method for preparing a multiphase CsBr / Cs3Bi2Br3I6 array thin film according to claim 1, characterized in that: The steps of the spraying method in S2 are as follows: 200 μL of bismuth iodide solution is placed in an electric airbrush with a nozzle diameter of 0.3 mm; the interdigitated electrode with CsBr microspheres is preheated to 110°C, and then the nozzle is vertically aligned with the center of the interdigitated electrode. Spraying is performed 5-10 times at a distance of 5 cm from its surface. Then the interdigitated electrode is placed in a drying oven and heated at 115-125°C for 20-40 minutes to obtain a multiphase Cs3Bi2Br3I6 array film.

7. An application of a multiphase CsBr / Cs3Bi2Br3I6 array thin film, characterized in that: The composite CsBr / Cs3Bi2Br3I6 array thin film prepared by any one of the preparation methods described in claims 1-6 is mounted on the fixed pin of the electrode to obtain a thin film-type composite CsBr / Cs3Bi2Br3I6 room temperature H2S gas sensor.

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