A method for preparing a self-supporting bismuth sulfide fiber membrane and its application in a flexible wide-spectrum photodetector

Abstract

A method for preparing a self-supporting bismuth sulfide fiber membrane and its application in a flexible wide-spectrum photodetector. The self-supporting Bi2S3 fiber membrane is prepared by a simple one-step hydrothermal method without using any template or organic matter. The self-supporting Bi2S3 fiber membrane is self-assembled by interweaving ultra-long one-dimensional nanowires with a length of up to millimeters and an aspect ratio greater than 1000, and its size can reach at least about 7 cm × 2.5 cm. More importantly, the self-supporting Bi2S3 fiber membrane has excellent flexibility and plasticity, can be bent at will and can be cut into any shape. A flexible wide-spectrum photodetector is constructed based on the prepared self-supporting Bi2S3 fiber membrane, which can achieve wide-spectrum detection from ultraviolet, visible to infrared bands in both flat and bent states, and has high responsiveness, fast response speed and excellent stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor detection materials and preparation thereof, and specifically relates to a preparation method of a self-supporting bismuth sulfide fiber membrane and application thereof in a flexible wide-spectrum photoelectric detector. Background Art

[0002] Wide-spectrum photodetectors are widely used in optical communications, biomedicine, environmental monitoring, and missile guidance because they can detect ultraviolet light, visible light, and infrared light at the same time. However, with the rapid development of science and technology, traditional wide-spectrum detectors that lack flexibility and mechanical strength can no longer meet the growing demand for flexible and wearable optoelectronic devices. Therefore, it is necessary to develop wide-spectrum photodetectors with high flexibility and excellent detection performance. Although there have been reports on related flexible wide-spectrum photodetectors, most of these devices are realized by transferring or preparing semiconductor materials on specific flexible substrates, and they are highly dependent on the substrate, which seriously limits the commercialization of flexible optoelectronic devices, especially in the wearable field. Therefore, exploring a flexible semiconductor material that can be synthesized without relying on a specific substrate is of great significance for the development of high-performance flexible wide-spectrum photodetectors.

[0003] Generally speaking, one-dimensional nanostructures, especially nanowires, not only have direct charge transfer paths, but also have large specific surface areas, high aspect ratios, and excellent mechanical flexibility, and are considered suitable for the development of flexible photodetectors with fast response speeds and strong bending detection capabilities. However, using a single nanowire structure to prepare a device may involve very complex photolithography processes, and its small effective area limits its practical application in large-area flexible and wearable fields. In contrast, fiber film devices based on a multitude of nanowires interwoven have greater advantages than single nanowires in large-area, flexible, and wearable fields. At the same time, fiber films can also maintain the advantages of single nanowires, namely, long photocarrier lifetime and short transit time, which is conducive to its application in flexible detection.

[0004] Ultra-long nanowires are crucial to forming highly flexible self-supporting films. Among many semiconductors, Bi2S3 is easy to prepare ultra-long nanowires due to its inherent one-dimensional chain structure and significant anisotropy, and then use it as the basic structure to obtain flexible fiber membranes. In addition, Bi2S3 is a typical narrow bandgap (1.3eV) material with high carrier mobility (~200cm 2 ·V -1 ·s -1 ), high optical absorption coefficient (~10 5 cm -1), abundant resources and environmental friendliness, and is considered to be a potential candidate material for the preparation of flexible wide-spectrum detectors. However, so far, there have been no reports on the preparation of large-area self-supporting Bi2S3 fiber membranes with nanowire network structures at home and abroad, especially on flexible wide-spectrum detection devices based on self-supporting Bi2S3 fiber membranes. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a self-supporting bismuth sulfide fiber membrane and its application in a flexible wide-spectrum photodetector. The present invention uses a hydrothermal method to prepare a self-supporting Bi2S3 fiber membrane for the first time, and designs a flexible wide-spectrum photodetector based on it. The method used in the present 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 flexible and wearable optoelectronics.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A self-supporting bismuth sulfide fiber membrane, wherein the fiber membrane is self-assembled by interweaving one-dimensional nanowires, the length of the one-dimensional nanowires can reach the millimeter level and the aspect ratio is greater than 1000.

[0008] A method for preparing the above-mentioned self-supporting bismuth sulfide fiber membrane is characterized in that: the method specifically comprises:

[0009] Step 1, prepare a sodium hydroxide solution with a concentration of 1-4 mol / L;

[0010] Step 2: add 0.5-1.5 mmol of thiourea to the sodium hydroxide solution prepared in step 1, then slowly add 0.2-0.6 mmol of bismuth oxide while stirring, and then stir thoroughly to obtain a precursor solution;

[0011] Step 3: Transfer the precursor solution obtained in step 2 to a high-pressure reactor with a filling degree of 30-80%, seal it and place it in a constant temperature heating drying oven for hydrothermal reaction;

[0012] Step 4: After the reaction is completed, the film is naturally cooled to room temperature, and the film close to the inner wall is taken out, washed, and naturally dried in the air to obtain a self-supporting bismuth sulfide fiber membrane.

[0013] Furthermore, in step 2, the molar ratio of thiourea to bismuth oxide is 5:2.

[0014] Furthermore, in step 2, the sufficient stirring time is 15-40 minutes.

[0015] Furthermore, in step three, the hydrothermal reaction temperature is 180-300° C., and the reaction time is 12-40 hours.

[0016] An application of the above-mentioned self-supporting bismuth sulfide fiber membrane in a flexible wide-spectrum photoelectric detector, wherein the detector is an MSM-type flexible detector, comprising a Bi2S3 fiber membrane and silver electrodes, wherein the silver electrodes are deposited at both ends of the Bi2S3 fiber membrane; the preparation method comprises the following steps: attaching a designed mask template to the surface of the self-supporting Bi2S3 fiber membrane, and depositing silver electrodes at both ends of the self-supporting Bi2S3 fiber membrane by electron beam evaporation, thermal evaporation or magnetron sputtering technology to obtain a Bi2S3 fiber membrane flexible photoelectric detector.

[0017] Furthermore, the thickness of the silver electrode is 30-60 nm, and the distance between the electrodes is 0.2-5 mm.

[0018] Furthermore, the bismuth sulfide fiber membrane is cut into any size less than or equal to 2.5 cm×7 cm, and the detector based thereon is made into a single device or a device array.

[0019] An application of the above-mentioned self-supporting bismuth sulfide fiber membrane in a flexible wide-spectrum photoelectric detector, the detector is a PEC-type flexible detector, including a flexible conductive substrate, a Bi2S3 fiber membrane, a solid electrolyte and a transparent flexible conductive substrate; the preparation method steps are: cutting the self-supporting Bi2S3 fiber membrane into a desired shape and attaching it to the conductive surface of the flexible conductive substrate, then coating the surface of the Bi2S3 fiber membrane with a solid electrolyte of the same shape and size, and finally covering it with another transparent flexible conductive substrate with the conductive surface facing down, and placing the whole in a vacuum drying oven for 24 hours to obtain a PEC-type flexible photoelectric detector.

[0020] Furthermore, the flexible conductive substrate is one of PET-ITO, aluminum foil or gold foil; the solid electrolyte is potassium hydroxide solid electrolyte; and the transparent flexible conductive substrate is PET-ITO.

[0021] The beneficial effects of the present invention over the prior art are as follows: without using any template or organic material, the present invention prepares a highly flexible self-supporting Bi2S3 fiber membrane that can be bent at any angle and cut into any shape by a simple one-step hydrothermal method. The Bi2S3 fiber membrane is self-assembled by interweaving ultra-long one-dimensional nanowires with a length of up to millimeters and an aspect ratio greater than 1000. The method of the present invention has simple process, good repeatability, low cost and environmental friendliness, and is suitable for large-scale industrial production. A flexible photodetector with simple process is designed based on the self-supporting Bi2S3 fiber membrane. The prepared detector can detect ultraviolet, visible and infrared light whether in a flat or bent state, and has high responsiveness, fast response characteristics and excellent stability. The present invention realizes the preparation of a self-supporting Bi2S3 fiber membrane for the first time, which shows good flexibility and plasticity. At the same time, the Bi2S3 fiber membrane flexible wide-spectrum photodetector prepared based on it also shows excellent detection performance before and after bending, which is of great significance to the development and application of flexible and wearable optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is an optical photograph of the self-supporting Bi2S3 fiber membrane prepared in Example 1 of the present invention;

[0023] Figure 2 This is an optical photograph of the self-supporting Bi2S3 fiber membrane prepared in Example 1 of the present invention in a continuous bending state;

[0024] Figure 3 Optical photographs of the self-supporting Bi2S3 fiber membrane prepared in Example 1 of the present invention being cut into different shapes;

[0025] Figure 4 This is a SEM image of the self-supporting Bi2S3 fiber membrane prepared in Example 1 of the present invention;

[0026] Figure 5 This is the XRD pattern of the self-supporting Bi2S3 fiber membrane prepared in Example 1 of the present invention;

[0027] Figure 6 This is a device structure diagram of the MSM type self-supporting Bi2S3 fiber membrane flexible photodetector prepared in Example 2 of the present invention;

[0028] Figure 7 This is a current curve diagram of the MSM type self-supporting Bi2S3 fiber membrane flexible photodetector prepared in Example 2 of the present invention when it is in a flat state under the irradiation of ultraviolet (365nm), visible (530nm) and infrared light (850nm);

[0029] Figure 8This is a current curve diagram of the MSM type self-supporting Bi2S3 fiber membrane flexible photodetector prepared in Example 2 of the present invention when it is in different bending states under the irradiation of infrared light (850nm);

[0030] Fig. 9 This is a device structure diagram of the PEC-type self-supporting Bi2S3 fiber membrane flexible photodetector prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention that does not depart from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0032] Embodiment 1:

[0033] A method for preparing a self-supporting Bi2S3 fiber membrane, the specific implementation steps are as follows:

[0034] A sodium hydroxide solution with a concentration of 2.5 mol / L was prepared, and then 1 mmol of thiourea and 0.4 mmol of bismuth oxide were added to the prepared sodium hydroxide solution in sequence while stirring. Stirring was continued for 20 minutes to obtain a precursor solution; it was then transferred to a 50 mL high-pressure reactor with a filling degree of 40%, sealed and placed in a constant temperature heating drying oven, subjected to hydrothermal reaction at 200°C for 24 hours, cooled to room temperature, took out the sample, and dried naturally in air to obtain a self-supporting Bi2S3 fiber membrane.

[0035] Figure 1 This is an optical photo of a self-supporting Bi2S3 fiber membrane, showing that its length and width can reach about 7 cm and 2.5 cm respectively. More importantly, mechanical deformation experiments show that ( Figure 2 ), under continuous bending, the Bi2S3 fiber membrane did not crack, showing excellent flexibility. In addition, the Bi2S3 fiber membrane can be cut into letters and arbitrary shapes, such as Figure 3 As shown. From the SEM image of Bi2S3 fiber membrane, it can be seen that ( Figure 4 ), the Bi2S3 fiber membrane is composed of a large number of dense nanowires with a diameter of 50-200nm and a length of at least 120μm. These nanowires are entangled with each other to form a randomly distributed network structure. Figure 5The XRD spectrum of the prepared Bi2S3 fiber membrane is shown. It can be seen that the five high-intensity diffraction peaks located at 2θ=15.84°, 17.76°, 22.56°, 25.16° and 35.88° are attributed to the (020), (210), (220), (130) and (240) crystal planes of Bi2S3, and the remaining diffraction peaks can also correspond well to the orthorhombic structure of Bi2S3 (JCPDS No. 65-2435). In addition, the peak shape of the XRD characteristic peak is sharp, indicating that the prepared Bi2S3 fiber membrane has a high crystal quality.

[0036] Embodiment 2:

[0037] A method for manufacturing a flexible wide-spectrum photodetector based on a self-supporting bismuth sulfide fiber film, the specific implementation steps are as follows:

[0038] The self-supporting Bi2S3 fiber membrane prepared in Example 1 was cut into 1 cm×1 cm, and then the designed mask was attached to the surface of the cut Bi2S3 fiber membrane. The precious metal silver was evaporated on both ends of the self-supporting Bi2S3 fiber membrane by electron beam evaporation technology to obtain a Bi2S3 fiber membrane flexible photodetector. Figure 6 Figure 3 is the corresponding device structure diagram, where the distance between electrodes is 1 mm.

[0039] Under the condition of bias voltage of 1V, the detection ability of Bi2S3 fiber film flexible photodetector was analyzed with incident light on / off for 10s as a cycle. Figure 7 As shown. Under UV light irradiation, the photocurrent increases rapidly, reaches a maximum value of about 1.73μA and remains stable. When the UV light is turned off, the photocurrent drops rapidly to the initial value. The detection performance of the Bi2S3 fiber film flexible photodetector in the visible light band was tested using visible light (530nm). The results show that the stable photocurrent of the device is as high as about 3.13μA. In addition, in order to obtain the photoresponse characteristics of the Bi2S3 fiber film flexible photodetector in the infrared band, light with a wavelength of 850nm was used as a simulated infrared light source. Under infrared light irradiation, the photocurrent increases sharply, reaches a maximum value (about 5.8μA) and then remains stable. When the infrared light is turned off, the photocurrent drops rapidly and returns to the initial value. It is worth noting that the change trend of the photocurrent after 5 on / off cycles of UV, visible light and infrared light is basically the same, which confirms that the Bi2S3 fiber film flexible photodetector has good stability and repeatability in the UV-visible-infrared band. Obviously, the prepared Bi2S3 fiber film flexible photodetector has excellent wide spectrum detection capability.

[0040] Bending resistance is a necessary prerequisite for the practical application of flexible photodetectors. In order to evaluate this ability, the detection performance of Bi2S3 fiber film photodetectors in a bent state was further studied under infrared light irradiation. Figure 8 shown. Figure 8 The illustrations show real photos of the Bi2S3 fiber membrane photodetector in different states. In the flat state (radius of 20mm), the Bi2S3 fiber membrane photodetector shows stable and fast detection capabilities for infrared light. When the Bi2S3 fiber membrane photodetector is in a bent state (bending radius of 15mm), the photocurrent increases rapidly under infrared light, and after no light, the photocurrent immediately drops to the initial value, and the maximum photocurrent only decreases slightly. After returning to the initial flat state, the photocurrent remains basically unchanged compared to before bending. In addition, the Bi2S3 fiber membrane photodetector exhibits stable and repeatable photoresponse characteristics in all tests, indicating that it has good flexibility and mechanical stability.

[0041] Embodiment 3:

[0042] A method for manufacturing a PEC-type flexible wide-spectrum photodetector based on a self-supporting bismuth sulfide fiber membrane, the specific implementation steps are as follows:

[0043] The self-supporting Bi2S3 fiber membrane prepared in Example 1 is cut into the required shape and attached to the conductive surface of the PET-ITO flexible substrate. Subsequently, a potassium hydroxide solid electrolyte of the same shape and size is coated on the surface of the Bi2S3 fiber membrane. Finally, another PET-ITO flexible substrate is covered on it with the conductive surface facing down. The whole is placed in a vacuum drying oven and dried for 24 hours to obtain a PEC-type flexible wide-spectrum photodetector based on the self-supporting Bi2S3 fiber membrane.

[0044] Fig. 9 This is a schematic diagram of the structure of the prepared PEC-type Bi2S3 fiber film flexible wide-spectrum photodetector. From the figure, it can be seen that the device structure is composed of a PET-ITO transparent flexible substrate, a self-supporting Bi2S3 fiber film and a solid electrolyte. Since both the substrate and the active material have good flexibility, the assembled PEC-type Bi2S3 fiber film photodetector also exhibits good flexibility and can detect ultraviolet, visible and infrared light under bending conditions. Obviously, Bi2S3 fiber film photodetectors have great application potential in the flexible and wearable fields.

Claims

1. A method for preparing a self-supporting bismuth sulfide fiber membrane, characterized in that: The fiber membrane is self-assembled by interweaving one-dimensional nanowires, the length of the one-dimensional nanowires is at the millimeter level and the aspect ratio is greater than 1000; the method is specifically: Step 1, prepare a sodium hydroxide solution with a concentration of 1-4 mol / L; Step 2: Add 0.5-1.5 mmol of thiourea to the sodium hydroxide solution prepared in step 1, then slowly add 0.2-0.6 mmol of bismuth oxide while stirring, and then stir thoroughly to obtain a precursor solution; the molar ratio of thiourea to bismuth oxide is 5:2; Step 3: transfer the precursor solution obtained in step 2 to a high-pressure reactor with a filling degree of 30-80%, seal it and place it in a constant temperature heating drying oven for hydrothermal reaction; the hydrothermal reaction temperature is 180-300 ° C, and the reaction time is 12-40 hours; Step 4: After the reaction is completed, the film is naturally cooled to room temperature, and the film close to the inner wall is taken out, washed, and naturally dried in the air to obtain a self-supporting bismuth sulfide fiber membrane.

2. The method for preparing the self-supporting bismuth sulfide fiber membrane according to claim 1, characterized in that: In step 2, the sufficient stirring time is 15-40 minutes.

3. Application of the self-supporting bismuth sulfide fiber membrane prepared by the preparation method of claim 1 in a flexible wide-spectrum photodetector, characterized in that: The detector is an MSM type flexible detector, comprising a Bi2S3 fiber membrane and silver electrodes, wherein the silver electrodes are deposited at both ends of the Bi2S3 fiber membrane; The preparation method comprises the following steps: attaching the designed mask plate to the surface of the self-supporting Bi2S3 fiber membrane, depositing silver electrodes on both ends of the self-supporting Bi2S3 fiber membrane by thermal evaporation or magnetron sputtering technology, and obtaining a Bi2S3 fiber membrane flexible photodetector.

4. The use according to claim 3, characterized in that: The thickness of the silver electrode is 30-60 nm, and the distance between the electrodes is 0.2-5 mm.

5. The use according to claim 3, characterized in that: The bismuth sulfide fiber membrane is cut into any size less than or equal to 2.5 cm×7 cm, and a detector based on the bismuth sulfide fiber membrane is made into a single device or a device array.

6. Application of the self-supporting bismuth sulfide fiber membrane prepared by the preparation method of claim 1 in a flexible wide-spectrum photodetector, characterized in that: The detector is a PEC-type flexible detector, and the preparation method comprises the following steps: cutting a self-supporting Bi2S3 fiber membrane into a desired shape and attaching it to the conductive surface of a flexible conductive substrate, then coating the surface of the Bi2S3 fiber membrane with a solid electrolyte of the same shape and size, and finally covering it with another transparent flexible conductive substrate with the conductive surface facing downward, and placing the whole in a vacuum drying oven for 24 hours to obtain a PEC-type flexible photodetector.

7. The use according to claim 6, characterized in that: The flexible conductive substrate is one of PET-ITO, aluminum foil or gold foil; the solid electrolyte is potassium hydroxide solid electrolyte; and the transparent flexible conductive substrate is PET-ITO.

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