Preparation method and application of indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrite broadband photoelectric detection material

Abstract

This invention belongs to the field of photoelectric detection material preparation technology, specifically relating to a preparation method and application of an indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic broadband photoelectric detection material. The method involves adding bismuth and indium source precursors to a solvent and stirring, then adding a sulfur source and continuing stirring to ensure uniform dispersion. The resulting precursor dispersion is subjected to a hydrothermal reaction at 140-220 °C. The cooled product is then centrifuged, washed, and vacuum dried to obtain the final product. The indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic broadband photoelectric detection material prepared by this invention exhibits a branched structure resembling a cactus, displaying multi-level and orderly branching characteristics. It exhibits sensitive and rapid photoelectric detection response in the ultraviolet-visible-near-infrared broadband range, enabling photoelectric detection from the ultraviolet to near-infrared bands without external pressure. This demonstrates significant application potential in fields such as high-efficiency light harvesting, photoelectrocatalysis, and high-performance photoelectric sensors.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric detection material preparation technology, specifically relating to a preparation method and application of an indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrite broadband photoelectric detection material. Background Technology

[0002] Indium sulfide and bismuth sulfide are both typical group VI semiconductor materials, possessing relatively narrow band gaps, high carrier mobility, and excellent photoresponse characteristics, showing significant potential in broadband photodetectors. By constructing indium sulfide / bismuth sulfide heterojunctions, effective control of the band structure can be achieved, enhancing light absorption and carrier separation efficiency in the ultraviolet, visible, and infrared bands, thereby improving the overall performance of the detector. Inspired by the high specific surface area and efficient mass transfer characteristics of branched structures in nature, biomimetic micron-sized dendritic structures have been introduced into heterojunction systems. This structure can significantly increase the light-harvesting interface, provide abundant carrier transport channels, and help alleviate interface defects caused by lattice mismatch, offering a new approach for the development of high-performance visible-infrared photodetectors.

[0003] In photoelectric detection applications, indium sulfide / bismuth sulfide heterojunctions, with their tunable band structure, exhibit high photoresponsivity and detectivity in the visible and near-infrared regions. Biomimetic micron-sized dendrite morphology further enhances the material's scattering and absorption of incident light, extending the optical path. Simultaneously, the one-dimensional, two-dimensional, and three-dimensional structures between dendrites facilitate efficient separation and rapid collection of photogenerated electron-hole pairs, improving device response speed and sensitivity. This characteristic makes them valuable for applications in fields with urgent needs for broadband, high-speed detection, such as environmental monitoring, bioimaging, security reconnaissance, and optical communication.

[0004] However, the preparation of indium sulfide / bismuth sulfide heterojunctions, especially the controllable synthesis with biomimetic dendritic structures, still faces many challenges. Existing heterojunction synthesis methods are mostly limited to single bismuth sulfide or indium sulfide materials, making it difficult to achieve simultaneous and precise control of morphology and interface structure. For example, patent CN105800687A discloses a method for preparing bismuth sulfide nanorods, using bismuth tungstate as the bismuth source and thioacetamide as the sulfur source. pH adjustment is required before the reaction, and a hydrothermal method is used to finally obtain one-dimensional bismuth sulfide nanorods. Furthermore, traditional methods often rely on organic templates, surfactants, or highly toxic solvents when constructing biomimetic micron-shaped morphologies with complex branching structures. This not only results in complex processes and high costs but may also introduce impurities that affect the photoelectric detection performance of the material. These problems severely restrict the practical application of indium sulfide / bismuth sulfide heterojunction semiconductor materials. Therefore, developing a simple, easy-to-implement, mild, environmentally friendly method for preparing indium sulfide / bismuth sulfide heterojunctions that allows for precise control of biomimetic dendritic morphology has become crucial for advancing this material towards practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing and applying a biomimetic micron-dendritic broadband photodetector material with indium sulfide / bismuth sulfide heterostructure. Using a one-step solvothermal method, biomimetic micron-dendritic structures with structures extremely similar to those of the "Opuntia ficus-indica" cactus were successfully synthesized without the need for any external templates or morphology guiding agents. These biomimetic micron-dendritic structures have a huge specific surface area and abundant surface states and defect energy levels. They exhibit sensitive and rapid photodetection response in the ultraviolet-visible-near-infrared broadband range and can achieve photodetection from the ultraviolet to the near-infrared band without the need for external pressure.

[0006] This invention is specifically achieved through the following technical solution: A method for preparing an indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic broadband photodetector material, according to this invention, specifically includes the following steps: (1) Take two metal precursors, bismuth source and indium source, and add them to the solvent. Stir continuously at room temperature for 30-60 min to fully dissolve and mix the precursors. Then, add sulfur source and continue stirring at room temperature for 30-60 min to obtain precursor dispersion. (2) Transfer all the obtained precursor dispersion into the polytetrafluoroethylene liner of the stainless steel hydrothermal reactor, place the reactor in an oven, and react at a constant temperature of 140-220 ℃ for 8-24 h. After the reaction is completed, stop heating and allow the reactor to cool naturally to room temperature in the oven. (3) The mixed product after cooling in the reactor is centrifuged and washed, and the washed precipitate is vacuum dried to obtain brown powder indium sulfide / bismuth sulfide heterostructure biomimetic micron dendrite material.

[0007] The aforementioned method for preparing indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrite broadband photodetector material, wherein the bismuth source is selected from one or more of bismuth acetate, bismuth chloride, bismuth oxide, and bismuth nitrate pentahydrate, the indium source is selected from one or more of indium chloride, indium oxide, indium acetate, and indium nitrate, and the sulfur source is selected from C8-C18 alkyl thiols.

[0008] Furthermore, the molar ratio of indium source to bismuth source is greater than 5:2, and the ratio of the total molar number of indium source and bismuth source to the molar number of thiol is less than 2:3.

[0009] In the aforementioned method for preparing the indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrite broadband photodetector material, the solvent is selected from at least one of ethanol, ethylene glycol, and isopropanol, and the polytetrafluoroethylene liner has a filling degree of 40-80%.

[0010] The aforementioned method for preparing indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrite broadband photodetector material, the centrifugal washing method in step (3) includes: transferring the cooled mixed product in the reaction vessel to a centrifuge tube, adding double-distilled water, centrifuging and discarding the supernatant, and collecting the precipitate; washing the precipitate with deionized water 3-5 times by centrifugation, and then washing it with anhydrous ethanol 3-5 times by centrifugation.

[0011] Furthermore, the vacuum drying temperature in step (3) is 40-80 ℃ and the time is 10-20 h.

[0012] The aforementioned method for preparing indium sulfide / bismuth sulfide heterojunction biomimetic micron dendritic broadband photodetector material yields an indium sulfide / bismuth sulfide heterojunction biomimetic micron dendritic material with a branched structure resembling a cactus, exhibiting multi-layered and orderly branching structural characteristics. The diameter of the entire biomimetic micron dendrite is 15 μm, and the entire biomimetic micron dendrite is composed of multiple one-dimensional rod-shaped structures growing in different orientations. The diameter of the one-dimensional rod-shaped structure is 0.5-2 μm, and two-dimensional nanosheets are uniformly attached to the surface of the one-dimensional rod-shaped structure. The two-dimensional nanosheets are interwoven with each other, and the thickness of the two-dimensional nanosheets is 100 nm, with a length of 500-2000 nm.

[0013] The present invention also provides an indium sulfide / bismuth sulfide heterojunction biomimetic micron dendritic material prepared according to the aforementioned preparation method and its application in photodetectors.

[0014] This invention also provides a photodetector comprising an indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic material prepared according to the aforementioned method. For example, the photodetector includes fluorine-doped indium tin oxide glass (FTO), with an indium sulfide / bismuth sulfide heterojunction film coated on one side of the FTO. The thickness of the indium sulfide / bismuth sulfide heterojunction film is controlled within the range of 300-1000 nm by adjusting the spin coater speed (800-3000 rpm). A silver electrode is printed on the indium sulfide / bismuth sulfide heterojunction film. This photodetector exhibits good self-powered photodetector response under irradiation at 365 nm, 625 nm, and 980 nm light sources, demonstrating stable switching irradiation cycles and strong light sensitivity. This demonstrates that the indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic material prepared according to this invention possesses a sensitive and rapid photodetector response in the ultraviolet-visible-near-infrared wide wavelength range.

[0015] Compared with existing technologies, this invention has significant advantages and beneficial effects. Through the above technical solution, this invention achieves considerable technological advancement and practicality, and has broad application value, possessing at least the following advantages: (1) The process of this invention is simple. It can directly obtain biomimetic micron dendrites with complex hierarchical structures of indium sulfide / bismuth sulfide heterojunctions using a one-step solvothermal method. The entire process involves only conventional solvothermal reaction and centrifugal washing and drying operations. The conditions are mild and the repeatability is good. It provides a simple and reliable path for the controllable preparation and large-scale production of biomimetic micron dendrite materials with complex hierarchical structures of indium sulfide / bismuth sulfide heterojunctions.

[0016] (2) This invention has good versatility and flexibility in the selection of raw materials. The bismuth source can be bismuth acetate, bismuth chloride, bismuth oxide, or bismuth nitrate pentahydrate; the indium source can be indium chloride, indium oxide, indium nitrate, or indium acetate; the sulfur source is an alkyl thiol with an alkyl chain length of C8-C18; and the solvent is a common alcohol such as ethanol, ethylene glycol, or isopropanol. The raw materials are low in cost and easy to obtain, which is conducive to the promotion and application of the technology.

[0017] (3) The highlight of this invention is that it successfully synthesizes biomimetic micron dendrites with a structure extremely similar to that of the "Opuntia ficus-indica" cactus using a one-step solvothermal method without the need for any external templates or morphology guiding agents. The biomimetic micron dendrites of this structure simultaneously contain one-dimensional rod-shaped units, two-dimensional nanosheet units, and three-dimensional biomimetic hierarchical dendrites assembled from them. Its formation is the result of the synergistic effect of reaction kinetics, intrinsic crystal growth, and heterojunction interface coupling. The specific mechanism is as follows: Dual Functions and Reaction Kinetic Regulation of Thiols: C8-C18 alkyl thiols play a dual role as both sulfur source and ligand in the reaction system. Under solvothermal high-temperature conditions, thiols gradually decompose to release sulfur. 2- The ions provide a relatively mild and continuous supply of sulfur, which is conducive to the formation of uniform initial crystal nuclei. At the same time, their long alkyl chains exert adsorption or steric hindrance effects on specific crystal faces, guiding the anisotropic growth of the crystal to a certain extent.

[0018] Alcohol solvent environment and synergistic growth of heterojunctions: Alcohol solvents not only provide the reaction medium, but their viscosity, coordination ability, and physicochemical properties at high temperatures also significantly influence the dissolution, transport, and crystallization processes of the precursors. Within a defined temperature range (140-220 °C), bismuth and indium source precursors gradually hydrolyze and react with the sulfur source. Bismuth sulfide and indium sulfide crystals begin nucleation and growth following their intrinsic growth habits. Due to the matching of their lattice parameters and the coordination of reaction kinetics, a tightly bound heterojunction is formed, rather than an independent mixture.

[0019] Self-assembly of multi-level biomimetic structures: The reaction-generated one-dimensional bismuth sulfide rod-shaped structure serves as the framework, upon which two-dimensional indium sulfide nanosheets are selectively deposited and assembled. This is primarily due to the inherent anisotropy of the crystal structures of both. Bismuth sulfide belongs to the orthorhombic crystal system, with its crystal structure extending along the c-axis. The Bi-S bonds within the chains are strong covalent bonds, while the chains are connected by relatively weak van der Waals forces. This strong structural anisotropy causes the growth rate of bismuth sulfide along the c-axis to be much faster than in other directions, thus driving the formation of the one-dimensional bismuth sulfide rod-shaped morphology. The long alkyl chains of thiols can be selectively adsorbed on the sides of the crystal structure, effectively inhibiting lateral growth and thus enhancing the anisotropic extension of the crystal along the one-dimensional direction, promoting the formation of the one-dimensional rod-shaped structure. In contrast, indium sulfide has a layered structure, belonging to the tetragonal crystal system. Its crystals are composed of stacked In-S layers, with strong In-S bond bonding within the layers and weak van der Waals forces connecting the layers. This structure tends to grow in two-dimensional planes. In the subsequent growth stages, driven by the reduction in the system's surface energy and aided by crystal growth mechanisms such as Oswald ripening and directional attachment, these indium sulfide two-dimensional nanosheets, guided by a one-dimensional bismuth sulfide rod-like structure, undergo lateral splicing and longitudinal extension growth. This multi-step self-assembly process morphologically highly mimics the multi-level, ordered branching structure of a cactus, ultimately successfully constructing a complex hierarchical structure integrating one-dimensional rod-like units, two-dimensional nanosheets, and three-dimensional biomimetic dendrites. The process method of this invention achieves controllable synthesis of multi-scale, multi-dimensional composite structures using only a simple chemical system and adjustable process parameters, demonstrating its promising potential for preparing customized micro- and nanostructures in fields such as biomimetic material design and photoelectrocatalysis.

[0020] (4) The XRD pattern of the indium sulfide / bismuth sulfide biomimetic micron-dendritic material synthesized in this invention proves that the indium sulfide and bismuth sulfide phases form a heterojunction structure. The indium sulfide / bismuth sulfide heterojunction absorbs in the wavelength range of 200-800 nm, and the absorption at 800 nm is not zero, indicating that the prepared indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic material has a wide-band detection capability in the ultraviolet-visible-near infrared range. The photodetector assembled from the indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic material has good self-powered photodetector response under ultraviolet-visible-near infrared irradiation at 365 nm, 625 nm, and 980 nm, and exhibits a stable switching irradiation cycle. It can achieve sensitive and fast photodetection from the ultraviolet, visible to near infrared bands without the need for external bias voltage, showing important application potential in the fields of high-efficiency light capture, photoelectrocatalysis, solar energy conversion devices, and high-performance photoelectric sensors. Attached Figure Description

[0021] Figure 1 This is a SEM image of the biomimetic micron dendrites of the indium sulfide / bismuth sulfide heterostructure synthesized in Example 1.

[0022] Figure 2 This is the XRD pattern of the biomimetic micron dendrites of the indium sulfide / bismuth sulfide heterojunction synthesized in Example 1.

[0023] Figure 3 This is the UV-Vis absorption spectrum of the biomimetic micron dendrites of the indium sulfide / bismuth sulfide heterojunction synthesized in Example 1.

[0024] Figure 4 The current-time (It) curves of the photodetector fabricated using the indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrite synthesized in Example 1 under irradiation by light sources of different wavelengths are shown.

[0025] Figure 5 This is a SEM image of the biomimetic micron dendrites of the indium sulfide / bismuth sulfide heterostructure synthesized in Example 2.

[0026] Figure 6 This is a SEM image of the biomimetic micron dendrites of the indium sulfide / bismuth sulfide heterojunction synthesized in Example 3. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The present invention will be described in detail below with reference to specific embodiments. Unless otherwise specified, all conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Raw materials and reagents whose manufacturers are not specified are all commercially available products.

[0029] Example 1: (1) Weigh 0.9 mmol of indium acetate and 0.1 mmol of bismuth chloride and place them in a 50 mL beaker. Add 30 mL of ethanol as a solvent and stir continuously at room temperature for 30 min to ensure that the precursor metal salt is fully dissolved and mixed evenly. Then, add 3 mmol of n-octadecyl mercaptan as a sulfur source and continue stirring at room temperature for 30 min to ensure that the n-octadecyl mercaptan is fully dispersed and pre-complexed with the metal ions to obtain the precursor dispersion. (2) Transfer all of the obtained precursor dispersion into a 50 mL polytetrafluoroethylene (PTFE) liner, place the PTFE liner in a stainless steel hydrothermal reactor and seal it, controlling the filling degree of the reaction system to be about 70%. Move the reactor to an oven and react at a constant temperature of 200℃ for 18 h. After the reaction is completed, stop heating and allow the reactor to cool naturally to room temperature in the oven. (3) Transfer the cooled mixture from the reactor in step (2) to a 50 mL centrifuge tube, add 10 mL of double-distilled water, centrifuge, discard the supernatant, and collect the precipitate. Wash the precipitate three times with deionized water and then three times with anhydrous ethanol to remove impurities. Dry the washed precipitate in a vacuum drying oven at 60 °C for 10 h to obtain an indium sulfide / bismuth sulfide heterojunction sample.

[0030] Figure 1 This is a SEM image of the indium sulfide / bismuth sulfide heterojunction sample obtained in this embodiment. Figure 1 It can be observed that the indium sulfide / bismuth sulfide heterojunction highly mimics the branching structure of a cactus in its macroscopic morphology, exhibiting obvious multi-level, ordered branching characteristics. The main body of the indium sulfide / bismuth sulfide heterojunction sample consists of dozens of one-dimensional rod-like structures growing in different orientations. The diameter of the one-dimensional rod-like structures is about 1-2 μm, exhibiting obvious anisotropy. Further observation reveals that two-dimensional nanosheet structures are uniformly attached to the surface of these one-dimensional rod-like structures. The nanosheets are about 100 nm thick and have a length in the range of 500-2000 nm. These two-dimensional nanosheets are interwoven with each other, forming abundant secondary branches. This morphological feature indicates that the indium sulfide / bismuth sulfide heterojunction obtained in this embodiment successfully integrates one-dimensional rod-like units and two-dimensional sheet-like units to form three-dimensional biomimetic micron dendrites, possessing typical multi-level composite characteristics. Figure 1 It can also be observed that the diameter of the entire biomimetic micron dendrite is about 15 μm, and it exhibits a distinctly dispersed state.

[0031] Figure 2 The image shows the XRD pattern of the obtained indium sulfide / bismuth sulfide heterojunction. A series of clear and high-intensity diffraction peaks can be observed. Comparison with standard diffraction cards for indium sulfide (JCPDS#65-0459) and bismuth sulfide (JCPDS#17-0320) reveals that the diffraction peaks of the heterojunction sample correspond to the (311) and (440) crystal planes of indium sulfide, respectively, while the other diffraction peaks correspond to the (220), (310), (211), and (221) crystal planes of bismuth sulfide. Bismuth sulfide exhibits stronger diffraction peaks due to its higher crystallinity. This result confirms that the synthesized sample is a heterojunction material composed of two phases, indium sulfide and bismuth sulfide, and that both maintain good crystallinity in the composite structure.

[0032] Figure 3This is the UV-Vis absorption spectrum of the obtained indium sulfide / bismuth sulfide heterojunction, from... Figure 3 It can be observed that the indium sulfide / bismuth sulfide heterojunction absorbs light in the wavelength range of 200-800 nm, and the absorption at 800 nm is not zero. This indicates that the indium sulfide / bismuth sulfide heterojunction sample can absorb near-infrared light, thus confirming that the prepared indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrites have a wide-band detection capability of ultraviolet-visible-near-infrared.

[0033] A suitable amount of the indium sulfide / bismuth sulfide heterojunction sample prepared in Example 1 was taken, and a certain amount of anhydrous ethanol was added. The mixture was ultrasonically dispersed for 30 s to obtain a uniform slurry with an indium sulfide / bismuth sulfide heterojunction concentration of 5 mg / mL. The slurry was then spin-coated onto fluorine-doped indium tin oxide (FTO) glass. The film thickness was controlled within the range of 300-1000 nm by adjusting the spin coater speed (800-3000 rpm), and the film was cured at room temperature. Subsequently, a silver electrode with a thickness of approximately 100-500 μm was fabricated on the film surface by screen printing, thus creating an indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic photodetector.

[0034] The current response of the indium sulfide / bismuth sulfide heterojunction biomimetic micro-dendritic photodetector under both illumination and no-illumination conditions was tested using a Keithley 2400 digital source meter to evaluate its photodetector performance. The silver electrode of the indium sulfide / bismuth sulfide heterojunction biomimetic micro-dendritic photodetector was brought into contact with the probe of the Keithley 2400 digital source meter. The illumination state was switched by controlling the opening and closing of the shutter, with a 10-second on-time and 10-second off-time, each cycle being 20 seconds. Two cycles were tested for each irradiation wavelength. Under zero bias conditions, the periodic irradiation and interruption of illumination were achieved by controlling the opening and closing of the shutter. When the shutter was open, the indium sulfide / bismuth sulfide heterojunction biomimetic micro-dendritic material was irradiated, and its internal electrons were excited to transition from the ground state to the excited state, generating a photocurrent. This current was led out through the silver electrode and acquired in real time by the It measurement unit of the Keithley 2400 digital source meter. When the shutter closes, the light stops, the excited electrons return to the ground state, and the photocurrent disappears.

[0035] Based on the above testing methods, the photoelectric performance of the indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrite photodetector was characterized, and the current-time (It) curves of the photodetector under irradiation with different wavelength light sources were obtained. The results are as follows. Figure 4 As shown. By Figure 4It can be seen that under light irradiation at wavelengths of 365 nm, 625 nm, and 980 nm, the photodetector can rapidly generate photocurrent and reach the peak response instantaneously; within 10 seconds of continuous illumination, the photocurrent exhibits a slight decay. After the illumination is interrupted, the photocurrent disappears rapidly, indicating that the prepared photodetector has obvious optical switching characteristics. Therefore, the indium sulfide / bismuth sulfide heterojunction photodetector assembled in this embodiment exhibits good self-powered photodetector response under ultraviolet-visible-near-infrared light irradiation at 365 nm, 625 nm, and 980 nm, demonstrating stable switching light irradiation cycling.

[0036] The superior ultraviolet-visible-near-infrared broadband self-powered photoelectric detection performance exhibited by the indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic structure stems from the synergistic effect of its unique multi-level biomimetic structure and intrinsic heterojunction effect. This indium sulfide / bismuth sulfide heterojunction is composed of one-dimensional rod-shaped structures (approximately 1-2 μm in diameter) and two-dimensional nanosheets (approximately 100 nm thick and 500-2000 nm long) attached to these one-dimensional rod-shaped structures, forming an open three-dimensional branched structure that highly mimics the shape of a cactus. The diameter of the entire biomimetic micron-dendritic structure can reach approximately 15 μm. This multi-scale composite structure not only provides a huge specific surface area and introduces abundant surface states and defect energy levels, acting as intermediate steps to promote multi-step absorption of sub-bandgap photons (such as in the near-infrared band) and expand the photoresponse range, but also, its fractal geometry and rough surface constitute an efficient photon management network. Through multiple reflections and scattering, it significantly enhances the optical path, enabling the material to fully capture photons across a wide wavelength range from ultraviolet to visible and even near-infrared (with significant absorption at 980 nm), ensuring sufficient photogenerated carrier concentration in self-powered mode. More importantly, its XRD pattern confirms that the material is a heterojunction composed of well-crystallized indium sulfide and bismuth sulfide phases. At the interface where the nanosheets and microrods are in close contact, the difference in band structure creates a locally built-in electric field throughout the dendritic network. These locally built-in electric fields effectively drive the spatial separation of photogenerated electron-hole pairs, producing a significant photovoltaic effect, thus enabling sensitive and rapid photoelectric detection from the ultraviolet, visible, to near-infrared bands without the need for external bias voltage.

[0037] Example 2: (1) Weigh 0.75 mmol of indium chloride and 0.15 mmol of bismuth acetate and place them in a 50 mL beaker. Add 30 mL of isopropanol as a solvent and stir continuously at room temperature for 30 min to ensure that the precursor metal salt is fully dissolved and mixed evenly. Then, add 4 mmol of n-hexadecyl mercaptan as a sulfur source and continue stirring at room temperature for 30 min to ensure that n-hexadecyl mercaptan is fully dispersed and pre-complexed with the metal ions to obtain a precursor dispersion. (2) Transfer all of the obtained precursor dispersion into a 50 mL polytetrafluoroethylene (PTFE) liner, place the PTFE liner in a stainless steel hydrothermal reactor and seal it, controlling the filling degree of the reaction system to be about 80%. Move the reactor to an oven and react at a constant temperature of 180°C for 22 h. After the reaction is completed, stop heating and allow the reactor to cool naturally to room temperature in the oven. (3) Transfer the cooled mixture from the reactor in step (2) to a 50 mL centrifuge tube, add 10 mL of double-distilled water, centrifuge, discard the supernatant, and collect the precipitate. Wash the precipitate three times with deionized water and then three times with anhydrous ethanol to remove impurities. Dry the washed precipitate in a vacuum drying oven at 50 °C for 12 h to obtain an indium sulfide / bismuth sulfide heterojunction sample.

[0038] Figure 5 This is a SEM image of the indium sulfide / bismuth sulfide heterojunction sample synthesized in this embodiment. Figure 5 It can be observed that the obtained indium sulfide / bismuth sulfide heterojunction retains the characteristics of... Figure 1 The tested sample exhibits a biomimetic morphology similar to the "Ten Thousand Mountains" cactus. The main body of the indium sulfide / bismuth sulfide heterojunction is composed of numerous one-dimensional rod-like structures grown in different orientations. The diameter of these one-dimensional rod-like structures is approximately 0.6-1.2 μm, compared to... Figure 1 The one-dimensional rod-like structures are finer and more densely packed. Two-dimensional nanosheets are still attached to the surface of these one-dimensional rod-like structures, and these two-dimensional nanosheets interweave and intertwine to ultimately form three-dimensional, multi-level biomimetic micron-dendritic structures. The diameter of the entire micron-dendritic structure is approximately 15 μm, exhibiting a clearly dispersed state. This result confirms that the morphology of the indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic structure possesses good structural stability and reproducibility within a certain range of synthesis parameters.

[0039] Example 3: (1) Weigh 0.8 mmol of indium chloride and 0.2 mmol of bismuth chloride and place them in a 50 mL beaker. Add 30 mL of ethylene glycol as a solvent and stir continuously at room temperature for 30 min to ensure that the precursor metal salt is fully dissolved and mixed evenly. Then, add 5 mmol of n-dodecyl mercaptan as a sulfur source and continue stirring at room temperature for 30 min to ensure that the n-dodecyl mercaptan is fully dispersed and pre-complexed with the metal ions to obtain a precursor dispersion. (2) Transfer all of the obtained precursor dispersion into a 50 mL polytetrafluoroethylene (PTFE) liner, place the PTFE liner in a stainless steel hydrothermal reactor and seal it, controlling the filling degree of the reaction system to be about 75%. Move the reactor to an oven and react at a constant temperature of 160℃ for 24 h. After the reaction is completed, stop heating and allow the reactor to cool naturally to room temperature in the oven. (3) Transfer the cooled mixture from the reactor in step (2) to a 50 mL centrifuge tube, add 10 mL of double-distilled water, centrifuge, discard the supernatant, and collect the precipitate. Wash the precipitate three times with deionized water and then three times with anhydrous ethanol to remove impurities. Dry the washed precipitate in a vacuum drying oven at 40 °C for 16 h to obtain an indium sulfide / bismuth sulfide heterojunction sample.

[0040] Figure 6 This is a SEM image of the indium sulfide / bismuth sulfide heterojunction sample prepared in this embodiment. From the image, it can be observed that the obtained indium sulfide / bismuth sulfide heterojunction retains the characteristics of... Figure 1 and Figure 5 The tested samples exhibited a biomimetic morphology similar to that of a cactus, demonstrating the good reproducibility of the preparation method of this invention. Further observation revealed that the entire indium sulfide / bismuth sulfide heterojunction is composed of numerous one-dimensional rod-like structures grown in different orientations. These rod-like structures have a diameter of approximately 1-2 μm and exhibit significant anisotropy. Two-dimensional nanosheets are attached to the surface of these one-dimensional rod-like structures, and these nanosheets interweave and intertwine to form three-dimensional multi-level biomimetic micron-dendritic structures. The entire micron-dendritic structure has a diameter of approximately 15 μm and exhibits a clearly dispersed state. Compared to Examples 1-2, when the bismuth source ratio increases, the two-dimensional nanosheets embedded in the surface of the one-dimensional rod-like structures become more densely packed, while numerous fine nanorods (50-100 nm in diameter, 1-2 μm in length) adorn the dendrite surface, further enriching its multi-level composite morphology.

[0041] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a wide-band photodetector material of indium sulfide / bismuth sulfide heterojunction biomimetic micro-branching crystals, characterized in that, Includes the following steps: (1) Take two metal precursors, bismuth source and indium source, and add them to the solvent. Stir continuously at room temperature for 30-60 min to fully dissolve and mix the precursors. Then, add sulfur source and continue stirring at room temperature for 30-60 min to obtain precursor dispersion. (2) Transfer all the obtained precursor dispersion into the polytetrafluoroethylene liner of the stainless steel hydrothermal reactor, place the reactor in an oven, and react at a constant temperature of 140-220 ℃ for 8-24 h. After the reaction is completed, stop heating and allow the reactor to cool naturally to room temperature in the oven. (3) The mixed product cooled in the reactor was centrifuged and washed, and the washed precipitate was vacuum dried to obtain indium sulfide / bismuth sulfide heterostructure biomimetic micron dendrite material.

2. The method for preparing the indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic broadband photodetector material as described in claim 1, characterized in that, The bismuth source is selected from one or more of bismuth acetate, bismuth chloride, bismuth oxide, and bismuth nitrate pentahydrate; the indium source is selected from one or more of indium chloride, indium oxide, indium acetate, and indium nitrate; and the sulfur source is selected from C8-C18 alkyl thiols.

3. The preparation method of the indium sulfide / bismuth sulfide heterojunction biomimicry micrometer dendrite broadband photodetector material according to claim 1 or 2, characterized in that, The molar ratio of indium source to bismuth source is greater than 5:2, and the ratio of the total molar number of indium source and bismuth source to the molar number of thiol is less than 2:

3.

4. The method for preparing the indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic broadband photodetector material as described in claim 1 or 2, characterized in that, The solvent is selected from at least one of ethanol, ethylene glycol, and isopropanol, and the filling degree of the polytetrafluoroethylene liner is 40-80%.

5. The method for preparing the indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic broadband photodetector material as described in claim 1, characterized in that, Step (3) The centrifugal washing method includes: transferring the cooled mixed product in the reactor to a centrifuge tube, adding double-distilled water, centrifuging and discarding the supernatant, and collecting the precipitate; washing the precipitate with deionized water 3-5 times by centrifugation, and then washing it with anhydrous ethanol 3-5 times by centrifugation.

6. The method for preparing the indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic broadband photodetector material as described in claim 1, characterized in that, Step (3) Vacuum drying temperature is 40-80 ℃, time is 10-20 h.

7. The method for preparing the indium sulfide / bismuth sulfide heterojunction biomimetic micron-dendritic broadband photodetector material as described in claim 1, characterized in that... The obtained indium sulfide / bismuth sulfide heterostructure biomimetic micron dendritic material has a branching structure resembling a cactus with "ten thousand mountains" (a metaphor for a complex structure), exhibiting multi-level and orderly branching structural characteristics. The diameter of the entire biomimetic micron dendrite is 15 μm. The entire biomimetic micron dendrite is composed of multiple one-dimensional rod-shaped structures growing in different orientations. The diameter of the one-dimensional rod-shaped structure is 0.5-2 μm. Two-dimensional nanosheets are uniformly attached to the surface of the one-dimensional rod-shaped structure. The two-dimensional nanosheets are interwoven with each other, and the thickness of the two-dimensional nanosheets is 100 nm, and the length is 500-2000 nm.

8. The indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrite material obtained by the preparation method according to claim 1.

9. The application of the indium sulfide / bismuth sulfide heterojunction biomimetic micron dendritic material obtained according to the preparation method of claim 1 in photodetectors.

10. A photodetector, characterized in that, Including the indium sulfide / bismuth sulfide heterojunction biomimetic micron dendrite material obtained by the preparation method of claim 1.

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