Preparation method and application of large-area honeycomb-like bismuth sulfide flexible film

Abstract

The invention discloses a preparation method and application of a large-area honeycomb-like bismuth sulfide flexible film, and belongs to the technical field of semiconductor detection materials and preparation thereof. A large-area honeycomb-like Bi2S3 flexible thin film is prepared by a low-pressure chemical vapor deposition method, and the flexible thin film is formed by arranging stable triangular unit structures, so that the flexible thin film is of an interconnected network structure. Wherein each triangular unit structure is formed by interweaving one-dimensional nanobelts which are regularly arranged. A flexible wide-spectrum photoelectric detector with a simple process is designed based on a large-area honeycomb-like Bi2S3 flexible thin film. The prepared detector can detect ultraviolet light, visible light and infrared light, and has high responsivity, quick response characteristic and excellent stability under a bending condition. More importantly, the device still shows excellent cycling stability and air stability after being continuously bent for a circle in the air without any packaging.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor detection materials and preparation thereof, and specifically relates to a preparation method of a large-area honeycomb-like bismuth sulfide flexible film and application thereof in a photoelectric detector. Background Art

[0002] With the development of modern science and technology, people's demand for wearable devices and foldable displays is increasing. As the core component of these flexible devices, flexible photodetectors have received more and more attention due to their flexibility, foldability and lightness. However, most flexible photodetection devices are currently realized by coating or transferring photoelectric materials on flexible substrates. The spin coating and transfer processes involved are complicated, and the transfer process will inevitably damage the materials. Such devices may have the problem of poor adhesion between the material and the substrate, which limits their detection ability under multiple bending or long-term continuous bending, and thus restricts the mechanical stability and bending durability of flexible photodetectors in practical applications. In addition, most flexible materials used as photoactive layers are composed of two-dimensional or three-dimensional structural units, which is not conducive to the acquisition of high-speed flexible photodetectors compared with one-dimensional structures. And compared with micron-scale materials, thin film materials that usually have larger lateral dimensions and exceed centimeter scales are easy to achieve large-scale device integration. Therefore, it is urgent to find a flexible thin film material that can be directly grown on a substrate and has a fast electron transfer channel. As we all know, one-dimensional structures have the advantages of large surface-to-volume ratio and direct electron transfer pathways, which can shorten the carrier transfer time. In particular, the honeycomb continuous film composed of interwoven one-dimensional structural units not only has a highly conductive network, but also facilitates the flexible device to achieve rapid detection and stable operation under long-term continuous bending. Considering that the triangle is the most stable shape among polygons, it can enhance the stability of the network structure, effectively disperse the external stress when subjected to external force, and has extremely high mechanical stability. Therefore, the honeycomb film composed of triangular structural units is expected to play an important application value in stable and high-performance flexible photodetectors.

[0003] As an emerging narrow bandgap material, Bi 2 S 3 It has the advantages of ideal carrier mobility, high light absorption coefficient, environmental protection, non-toxicity, abundant resources and low cost. 2 S 3 By chain (Bi 4 S 6 ) n band composition and anisotropy, which usually makes Bi 2 S 3Grown into one-dimensional nanostructures with direct charge transport pathways, large surface-to-volume ratios and aspect ratios, it is considered to be a very promising optoelectronic material. 2 S 3 Photodetectors are all based on single nanowires or nanoribbons. 2 S 3 The research on the flexible detection performance of flexible films has not been reported. Therefore, it is necessary to prepare a honeycomb Bi with high flexibility. 2 S 3 Flexible films are of great interest and a huge challenge. Therefore, it is necessary to develop large-area Bi composed of one-dimensional triangular structural units. 2 S 3 Flexible films can then be used to build high-performance flexible photodetectors. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a large-area honeycomb-like bismuth sulfide flexible film and its application in photoelectric detectors. The present invention uses chemical vapor deposition technology to prepare a large-area honeycomb-like Bi 2 S 3 Flexible film, and based on it, a flexible wide spectrum photodetector is designed. The method adopted by the invention has the advantages of simple operation, environmental friendliness and low cost, is suitable for large-scale industrial production, and has high application prospects in the field of optoelectronics.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a large-area honeycomb-like bismuth sulfide flexible film comprises the following steps:

[0007] Step 1: fix one side of the mica with double-sided tape, and peel off the mica layer by layer from the other side with a surgical blade until an extremely thin mica layer with excellent flexibility is obtained as a substrate;

[0008] Step 2: Place the freshly peeled surface of the substrate upward in the downstream area of ​​the airflow direction in the quartz tube, place bismuth oxide and sulfur powder as precursor sources in quartz boats respectively, then place sulfur powder in the upstream area of ​​the airflow direction in the quartz tube, and place bismuth oxide in the middle area between the substrate and sulfur powder in the quartz tube and in the heating center of the tube furnace;

[0009] Step 3: seal the quartz tube and evacuate it, then continue to pass argon gas for 15 minutes to purify the quartz tube;

[0010] Step 4: introduce carrier gas to make the quartz tube reach a specific pressure. After the pressure in the quartz tube is stable for a period of time, set the heating rate, reaction temperature and reaction time. After setting the program, start the reaction;

[0011] Step 5: After the reaction is completed and the sample is naturally cooled to room temperature, a large area of ​​honeycomb-like Bi is obtained. 2 S 3 Flexible film.

[0012] Furthermore, in step 1, the thickness of the substrate is about 50 μm-200 μm.

[0013] Furthermore, in step 2, the substrate is positioned 22-27 cm away from the gas outlet of the quartz tube, and the sulfur powder is positioned 27-30 cm away from the gas inlet of the quartz tube.

[0014] Furthermore, in step 4, the carrier gas is argon or nitrogen, the gas flow rate is 10-100 sccm, the pressure is 50-120 Pa, and the pressure stabilization time in the quartz tube is 10-30 min.

[0015] Furthermore, in step 4, the heating rate is 15-25°C / min, the reaction temperature is 550-620°C, and the reaction time is 1-15min.

[0016] An application of a honeycomb-like flexible bismuth sulfide film prepared by the preparation method, wherein the honeycomb-like flexible bismuth sulfide film is used in a photoelectric detector to prepare a flexible wide-spectrum photoelectric detector.

[0017] Furthermore, the flexible wide-spectrum photoelectric detector also includes a metal electrode, which is directly deposited on the surface of the honeycomb-like bismuth sulfide flexible film through a mask plate.

[0018] Furthermore, the metal electrode includes an Au electrode, a Cu electrode, an Ag electrode, a Cr electrode or a Ni electrode.

[0019] Furthermore, the metal electrode has a thickness of 30-100 nm and a width of 20-200 μm.

[0020] Furthermore, the metal electrode is deposited by electron beam evaporation, thermal evaporation or magnetron sputtering technology.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention prepares a large-area honeycomb-like Bi by low-pressure chemical vapor deposition. 2 S 3The flexible film is composed of a stable triangular unit structure arranged to form an interconnected network structure. The triangular unit structure is formed by regularly arranged one-dimensional nanoribbons interwoven with each other. The method of the invention has simple process, good repeatability, low cost and environmental friendliness, and is suitable for large-scale industrial production. 2 S 3 Flexible film is designed to be a flexible wide-spectrum photodetector with simple process. The prepared detectors can detect ultraviolet, visible and infrared light, and have high responsiveness, fast response characteristics and excellent stability under bending conditions. More importantly, the device still shows excellent cycle stability and air stability after being bent continuously in air for one week without any packaging. In addition, Bi 2 S 3 The thin film detector also has good flexible imaging capabilities. The present invention realizes a large-area honeycomb-like Bi composed of a triangular unit structure with strong stability. 2 S 3 Preparation of flexible films, and Bi 2 S 3 Flexible broadband photodetectors exhibit excellent detection performance and image recognition capabilities, which is of great significance for the further development of flexible broadband photoelectric devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The large-area honeycomb-like Bi prepared in Example 1 2 S 3 Optical photographs of flexible films;

[0024] Figure 2 The large-area honeycomb-like Bi prepared in Example 1 2 S 3 Atomic force microscopy images of flexible films;

[0025] Figure 3 The large-area honeycomb-like Bi prepared in Example 1 2 S 3 XRD pattern of flexible film;

[0026] Figure 4 Bi prepared in Example 2 2 S 3 Time-resolved photoresponse curves of the flexible broadband photodetector in the bent state under on / off conditions of ultraviolet (365nm), visible (470nm, 530nm, 625nm) and infrared (850nm, 940nm);

[0027] Figure 5 Bi prepared in Example 22 S 3 Time-resolved photoresponse curves of flexible broadband photodetectors in different bending states under infrared light on / off;

[0028] Figure 6 Bi prepared in Example 3 2 S 3 Image of a flexible broadband photodetector as a single-pixel sensing unit in a bent state;

[0029] Figure 7 Bi prepared in Example 3 2 S 3 Image of a flexible broadband photodetector as a single-pixel sensing unit when it returns to a flat state after being bent. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] The present invention discloses a method for preparing a large-area honeycomb-like bismuth sulfide flexible film and its application in a photoelectric detector. 2 S 3 The size of the flexible film can be at least 2cm×2cm. 2 S 3 The flexible film is composed of stable triangular basic structural units, which are arranged regularly to form a continuous network structure connected to each other. The triangular basic structural units are interwoven with one-dimensional nanoribbons, which are arranged at an angle of approximately 60° or 120°. 2 S 3 The flexible film constructs a flexible wide-spectrum photodetector, which can stably and quickly realize wide-spectrum detection from ultraviolet, visible to infrared bands, and exhibits excellent stability under bending conditions. In addition, the flexible detector can be used as a sensing pixel to obtain a clear target image, that is, it has good flexible image recognition ability. The present invention has developed a large-area honeycomb-like Bi 2 S 3 A method for preparing a flexible film, and based on it, a high-performance flexible wide-spectrum imaging detector was prepared, which has great practical value in the functional application of future flexible optoelectronic devices.

[0032] Embodiment 1:

[0033] This embodiment provides a large-area honeycomb-like Bi 2 S 3 The preparation method of the flexible film is specifically implemented in the following steps:

[0034] Fix one side of the mica with double-sided tape, and use a surgical blade to peel off the mica layer by layer from the other side until an extremely thin mica layer with excellent flexibility is obtained. Then place it with the freshly peeled side facing up in the downstream area of ​​the airflow direction in the quartz tube. Bismuth oxide and sulfur powder are placed in a quartz boat as precursor sources, and then placed in the central heating area of ​​the quartz tube and about 28.6 cm in the upstream area of ​​the airflow direction. Seal the quartz tube and evacuate it to a vacuum state, and then continue to pass high-purity argon gas to purify the quartz tube. Subsequently, high-purity argon gas with a gas flow rate of 30sccm is introduced to make the tube reach a specific pressure of 80Pa. Finally, set the tubular furnace to keep warm at 570°C for 3 minutes. After the reaction is completed and naturally cooled to room temperature, take out the sample to obtain a large area of ​​honeycomb-like Bi 2 S 3 Flexible film.

[0035] Figure 1 Honeycomb-like Bi 2 S 3 Optical photo of the flexible film, showing Bi 2 S 3 The film covers the entire mica substrate and its size can reach 2cm×2cm. At the same time, the film shows good bendability, indicating that the present invention has achieved centimeter-level honeycomb-like Bi 2 S 3 Preparation of flexible films. In order to more clearly observe Bi 2 S 3 The microscopic morphology of the film was characterized by atomic force microscopy, and the corresponding AFM images are shown in Figure 2 In. It can be seen that Bi 2 S 3 The nanoribbons are regularly arranged along three specific directions, forming a triangular structure with uniform depth, and are interconnected with each other, thus forming a large-scale honeycomb-like film with an interconnected network structure. Obviously, the triangular structure with uniform depth is regularly arranged along specific directions. Figure 3 The prepared honeycomb-like Bi 2 S 3 XRD spectrum of the flexible film. It can be seen that there are three peaks at 2θ = 22.4°, 24.9° and 51.2°, corresponding to the orthorhombic structure of Bi 2 S 3 Except for the diffraction peak of the mica substrate, no other characteristic peaks were observed, indicating that Bi2 S 3 The film has high crystalline quality.

[0036] Embodiment 2:

[0037] This embodiment provides a large-area honeycomb-like Bi 2 S 3 The preparation method of the flexible wide-spectrum photoelectric detector of the flexible film is specifically implemented as follows:

[0038] The honeycomb-like Bi prepared in Example 1 2 S 3 The flexible film is directly fixed on the evaporation table as an optoelectronic platform, and then the pre-designed mask is covered on its surface and optically aligned. It is placed in the evaporation chamber and sealed, and then vacuumed. When the evaporation degree reaches 10 -5 Pa, the electron beam evaporation is started, the metal is melted by adjusting the electron beam flow, and then the metal is evaporated on the honeycomb-like Bi according to the pre-designed electrode pattern. 2 S 3 Flexible film surface, that is, complete Bi 2 S 3 Fabrication of thin film flexible photodetectors.

[0039] The performance of flexible broadband photodetector is studied. The specific implementation steps are as follows: Under the condition of bias voltage of 0.1V, the Bi 2 S 3 The detection capability of the thin film flexible photodetector in a bent state (bending radius of 18 mm) was tested, and the time-resolved photoresponse obtained was as follows: Figure 4 As shown. Obviously, under the irradiation of 365nm ultraviolet light, the current rises rapidly to a maximum value of about 22.93μA, and after turning off the ultraviolet light, the photocurrent drops rapidly and returns to the initial value. When the device is irradiated with 470nm (blue light), 530nm (green light), 625nm (red light), 850nm and 940nm light, it also shows response characteristics consistent with ultraviolet light, and the maximum photocurrent reaches about 20.57, 18.42, 16.75, 8.43 and 3.08μA respectively. Note that under the irradiation of light of different wavelengths, Bi 2 S 3 The maximum photocurrent of the thin film flexible photodetector remains stable and does not decay over multiple cycles, which indicates that the device has stable, sustainable and repeatable excellent detection capabilities in a wide band from ultraviolet to infrared. In addition, the detection performance of the device at different bending radii was tested under infrared light, such as Figure 5 As shown. It can be seen that the prepared Bi 2 S 3 After bending (radius 18mm and 16mm), the thin film flexible photodetector maintains the same light response characteristics as in the flat state, and the photocurrent changes very slightly. 2 S 3 The thin-film flexible photodetector still exhibits repeatable photoresponse after switching the light source on and off multiple times. These results show that Bi 2 S 3 Thin-film flexible photodetectors have excellent stability and have broad application potential in flexible electronic devices and wearable devices.

[0040] Embodiment 3:

[0041] This embodiment provides a large-area honeycomb-like Bi 2 S 3 The application of flexible wide-spectrum photodetectors of flexible films in the field of image recognition is implemented in the following specific steps:

[0042] Due to the constructed Bi 2 S 3 Flexible photodetectors have excellent detection performance, so they can be used as pixels to further study flexible imaging functions, which is of great significance for future wearable, flexible display and medical devices. First, a visual imaging system was built, using the "100" digital mask fixed on the computer two-dimensional transfer platform as the imaging target, and placing it between the incident light source and the Bi constructed in Example 2. 2 S 3 Thin film flexible photodetectors. When incident light shines through the shadow mask onto Bi 2 S 3 When the thin film flexible photodetector is placed on the surface, the corresponding position-dependent current will be recorded in real time by the digital source meter and oscilloscope. At the same time, the recorded current signal will be further converted into a pixel image by the computer, such as Figure 6 As shown in the figure, when the device in the bent state is used as a single pixel sensing unit, the obtained "100" image shows clear boundaries and high fidelity characteristics. After bending and returning to the flat state, the device still shows good imaging ability as a single pixel ( Figure 7 ), which confirms that Bi 2 S 3 Application of thin film flexible photodetectors in image recognition.

[0043] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a large-area honeycomb-like bismuth sulfide flexible film, characterized in that: The following steps are involved: Step 1: peel off the mica to obtain an extremely thin mica layer as a substrate; Step 2: Place the freshly peeled surface of the substrate upward in the downstream area of ​​the airflow direction in the quartz tube, place the sulfur powder in the upstream area of ​​the airflow direction in the quartz tube, and place bismuth oxide in the middle area between the substrate and the sulfur powder in the quartz tube and at the heating center of the tube furnace; Step 3, sealing and evacuating the quartz tube, and then continuously introducing argon gas to purify the quartz tube; Step 4: introduce carrier gas to make the quartz tube reach a specific pressure. After the pressure in the quartz tube is stable for a period of time, set the heating rate, reaction temperature and reaction time to start the reaction; Step 5. After the reaction is completed and the film is naturally cooled to room temperature, the sample is taken out to obtain a large-area honeycomb-like Bi2S3 flexible film.

2. The preparation method according to claim 1, characterized in that: In step 1, the thickness of the substrate is about 50 μm-200μm.

3. The preparation method according to claim 1, characterized in that: In step 2, the substrate is positioned 22-27 cm away from the gas outlet of the quartz tube, and the sulfur powder is positioned 27-30 cm away from the gas inlet of the quartz tube.

4. The preparation method according to claim 1, characterized in that: In step 4, the carrier gas is argon or nitrogen, the gas flow rate is 10-100 sccm, the pressure is 50-120 Pa, and the pressure stabilization time in the quartz tube is 10-30 min.

5. The preparation method according to claim 1, characterized in that: In step 4, the heating rate is 15-25°C / min, the reaction temperature is 550-620°C, and the reaction time is 1-15min.

6. An application of a honeycomb-like bismuth sulfide flexible film prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The honeycomb-like bismuth sulfide flexible film is used in a photoelectric detector to prepare a flexible wide-spectrum photoelectric detector.

7. The use according to claim 6, characterized in that: The flexible wide-spectrum photoelectric detector also includes a metal electrode, which is directly deposited on the surface of the honeycomb-like bismuth sulfide flexible film through a mask plate.

8. The use according to claim 6, characterized in that: The metal electrode includes an Au electrode, a Cu electrode, an Ag electrode, a Cr electrode or a Ni electrode.

9. The use according to claim 6, characterized in that: The metal electrode has a thickness of 30-100 nm and a width of 20-200 μm.

10. The use according to claim 6, characterized in that: The metal electrode is deposited by electron beam evaporation, thermal evaporation or magnetron sputtering technology.

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