One-dimensional WS2 / WSe2 heterojunction materials, their preparation methods and applications

Abstract

This invention discloses a one-dimensional WS2 / WSe2 heterojunction material, its preparation method, and its applications, belonging to the field of nanomaterials technology. The one-dimensional WS2 / WSe2 heterojunction material is a one-dimensional structural material composed of alternating WS2 nanoribbons and WSe2 nanoribbons arranged along its width direction. Furthermore, this invention proposes a method for preparing the one-dimensional WS2 / WSe2 heterojunction material, comprising: arranging a WS2 source and a WSe2 source separately in a reaction apparatus, and placing a growth substrate loaded with salt halides in the nucleation growth region; heating to the growth temperature under a protective atmosphere to allow the WS2 source and WSe2 source to react sequentially; and obtaining the one-dimensional WS2 / WSe2 heterojunction material through catalytic induction of the salt halide by sequentially switching the effective supply of the WS2 source and WSe2 source. The one-dimensional WS2 / WSe2 heterojunction material proposed in this invention exhibits high crystallinity and a clear heterojunction interface.

Description

Technical Field

[0001] This invention relates to the field of low-dimensional semiconductor transition metal chalcogenide nanomaterials, specifically to one-dimensional WS2 / WSe2 heterojunction materials, their preparation methods, and applications. Background Technology

[0002] Transition metal dichalcogenides (TMDs) have attracted widespread attention in recent years in fields such as semiconductors, photodetectors, luminescence, and flexible electronics due to their layered crystal structure, tunable band gaps, strong light-matter interactions, and excellent electrical properties. WS2 and WSe2, as typical TMD materials, possess distinct band gaps, work functions, exciton behaviors, and carrier transport characteristics.

[0003] Existing research largely focuses on two-dimensional WS2 and WSe2 single materials and their planar (in-plane / out-of-plane) heterojunction structures. However, for WS2 / WSe2 heterojunction superlattice nanomaterials with periodic composition modulation along one-dimensional directions, especially one-dimensional structures with continuous interfaces, controllable composition, and the ability to achieve multi-period repetition, relevant preparation methods remain relatively limited. Traditional methods often suffer from the following problems: first, it is difficult to achieve precise heterojunction periodicity control along one-dimensional directions; second, severe interface diffusion leads to unclear heterojunction interfaces and severe alloying; and third, the resulting materials have low crystallinity and poor consistency, making it difficult to meet the requirements of device integration.

[0004] Therefore, developing a one-dimensional WS2 / WSe2 heterojunction material with simple processing, controllable parameters, and reproducible high crystal quality and clear heterojunction interface, as well as its preparation method, is of great significance for expanding the two-dimensional layered semiconductor heterostructure material system and promoting the miniaturization and integration of nanoelectronic and optoelectronic devices. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a one-dimensional WS2 / WSe2 heterojunction material, its preparation method and application, thereby solving the technical problem of how to obtain a one-dimensional WS2 / WSe2 heterojunction material with high crystallinity and clear heterostructure in the prior art.

[0006] To achieve the above technical objectives, the present invention provides a one-dimensional WS2 / WSe2 heterojunction material, wherein the heterojunction material is a one-dimensional structural material composed of WS2 nanoribbons and WSe2 nanoribbons arranged alternately along the width direction, and the WS2 nanoribbons and WSe2 nanoribbons are grown alternately to form multiple periodic heterojunction interfaces.

[0007] In any embodiment, the heterojunction material has a one-dimensional nanoribbon morphology.

[0008] In any embodiment, the length of the one-dimensional WS2 / WSe2 heterojunction material is 5-100 μm, the width is 1-20 μm, and the number of periods is 1-10, wherein the width of a single component nanoribbon is 14 nm-5 μm.

[0009] In any embodiment, the heterojunction interface is an atomically steep heterojunction interface.

[0010] Furthermore, this invention also proposes a method for preparing the above-mentioned one-dimensional WS2 / WSe2 heterojunction material, comprising the following steps: S1. Arrange the WS2 source and WSe2 source in predetermined positions within the reaction apparatus, and place the growth substrate loaded with salt halides in the nucleation growth region; S2. Under a protective atmosphere and a reducing atmosphere, the temperature is raised to the growth temperature, so that the WS2 source and the WSe2 source react sequentially. By switching the effective supply of the WS2 source and the WSe2 source in a time sequence, and with the catalytic induction of salt halides, the WS2 component and the WSe2 component are alternately epitaxially grown in the width direction of the one-dimensional nanoribbon to form the corresponding WS2 nanoribbon and WSe2 nanoribbon. The alternating arrangement of the WS2 nanoribbon and the WSe2 nanoribbon results in the one-dimensional WS2 / WSe2 heterojunction material.

[0011] In any embodiment, in step S1, the salt halide is one or more of KCl, NaCl, KI and NaI.

[0012] In any embodiment, in step S2, the growth temperature is 800℃~1150℃.

[0013] In any embodiment, in step S2, the single-component growth time supplied by the timing-switched WS2 source and WSe2 source is 1-3 min.

[0014] In any embodiment, the protective atmosphere and reducing atmosphere are a mixture of Ar, H2 and H2O or a mixture of N2, H2 and H2O, and the flow rate of the mixture is 10 to 200 sccm.

[0015] In any embodiment, in step S1, the reaction device is a tubular furnace quartz tube; in step S2, when the WS2 source is placed in the central heating zone of the tubular furnace, the heating time is 3 to 10 minutes, and when the WSe2 source is placed in the central heating zone of the tubular furnace, the heating time is 1 to 3 minutes.

[0016] The present invention also proposes the application of the above-mentioned one-dimensional WS2 / WSe2 heterojunction material or the one-dimensional WS2 / WSe2 heterojunction material prepared by the above preparation method in field-effect transistors, light-emitting devices, photodetectors, flexible electronic devices or nano-integrated devices.

[0017] Compared with existing technologies, the beneficial effects of this invention include: compared with existing two-dimensional planar heterojunction materials, the heterojunction material proposed in this invention has high crystallinity and clear heterojunction interfaces. The heterojunction material is a one-dimensional structure material composed of WS2 nanoribbons and WSe2 nanoribbons arranged alternately along the width direction. The alternating arrangement of WS2 nanoribbons and WSe2 nanoribbons forms multiple periodic heterojunction interfaces. This one-dimensional WS2 / WSe2 heterojunction material has high crystallinity and clear heterojunction interfaces. The periodic component modulation and multiple heterojunction interfaces formed by the one-dimensional superlattice structure can effectively confine the charge carriers within a one-dimensional scale, avoiding the scattering and diffusion of charge carriers in the traditional two-dimensional plane, thereby achieving high-efficiency transport, separation and collection of charge carriers along a predetermined direction.

[0018] The fabrication method proposed in this invention can precisely adjust the superlattice period, composition width, and superlattice interface quality through sequential power supply and control of growth time and temperature. It also exhibits good process compatibility and stability, making it suitable for subsequent device fabrication and large-scale production. This invention's fabrication method is simple, reproducible, and can yield one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials with clear interfaces, axial continuity, and high crystallinity. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the apparatus, precursor, and substrate arrangement for preparing materials according to Embodiment 1 of the present invention.

[0020] Figure 2 The one-dimensional WS2 / WS obtained in Embodiment 1 of this invention e2 A schematic diagram and optical photograph of the atomic structure of heterojunction superlattice nanomaterials; Figure 2 a is a schematic diagram of the atomic structure. Figure 2 b is an optical photograph.

[0021] Figure 3 These are transmission electron microscope and high-resolution transmission electron microscope images of the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials prepared in Example 1 of this invention.

[0022] Figure 4 This is an elemental spatial distribution mapping and a line scan distribution map along the superlattice width direction of the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial prepared in Example 1 of this invention; wherein, Figure 4 'a' represents the spatial distribution mapping of elements. Figure 4 b represents the elemental line scan distribution along the width of the superlattice.

[0023] Figure 5 These are characterization spectra of the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials prepared in Example 1 of this invention; wherein, Figure 5a, Figure 5 b and Figure 5 c stands for Raman mapping. Figure 5 d is the Raman spectrum. Figure 5 e is the photoluminescence spectrum.

[0024] Figure 6 This is a SEM image of the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial prepared in Example 2 of this invention. Figure 6 a, Figure 6 b、 Figure 6 c and Figure 6 d represents a heterojunction superlattice structure obtained by controlling the growth time of a single-component WSe2. Figure 6 e is used to control the growth time and number of reactions of WS2 / WSe2 (3 s, 7 times) to obtain heterojunction superlattice structures with different widths.

[0025] Figure 7 This is a photograph of the one-dimensional WS2 single-component nanoribbons prepared in Comparative Example 1 of this invention.

[0026] Figure 8 This is a photograph of the two-dimensional WS2 / WSe2 nanosheets prepared in Comparative Example 2 of this invention.

[0027] Figure 9 The image shows the photoresponse IV characteristics of photodetectors constructed from the materials prepared in Example 1 (i.e., 1D WS2 / WSe2), Comparative Example 1 (i.e., 1D WS2 nanoribbon), and Comparative Example 2 (i.e., 2D WS2 / WSe2) of this invention.

[0028] Explanation of reference numerals in the attached figures: 1. Magnet; 2. Tube furnace; 3. Substrate; 4. Quartz rod; 5. WS2 powder; 6. WSe2 powder; 7. Heterojunction superlattice interface. Detailed Implementation

[0029] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0030] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0031] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0032] This specific embodiment provides a one-dimensional WS2 / WSe2 heterojunction material. The heterojunction material is a one-dimensional structural material composed of WS2 nanoribbons and WSe2 nanoribbons arranged alternately along the width direction. The WS2 nanoribbons and WSe2 nanoribbons are grown alternately to form multiple periodic heterojunction interfaces. The morphology of the heterojunction material is a one-dimensional nanoribbon morphology. The length of the one-dimensional WS2 / WSe2 heterojunction material is 5-100 μm, the width is 1-20 μm, and the number of periods (i.e., the number of times the reaction source is switched) is 1-10. The width of a single component nanoribbon is 14 nm-5 μm. The heterojunction interface is an atomically steep heterojunction interface.

[0033] Furthermore, this specific embodiment also proposes a method for preparing the above-mentioned one-dimensional WS2 / WSe2 heterojunction material, including the following steps: S1. Arrange the WS2 source and WSe2 source at predetermined positions within the reaction apparatus, and place the growth substrate loaded with salt halides in the nucleation growth region; the salt halides are one or more of KCl, NaCl, KI and NaI; the reaction apparatus is a tubular furnace quartz tube; S2. Under a protective and reducing atmosphere, the temperature is raised to the growth temperature, causing the WS2 source and WSe2 source to react sequentially. By switching the effective supply of the WS2 source and WSe2 source in a time-sequential manner, and with the catalytic induction of salt halides, the WS2 component and WSe2 component are alternately epitaxially grown in the width direction of the one-dimensional nanoribbon to form corresponding WS2 nanoribbons and WSe2 nanoribbons. The alternating arrangement of the WS2 nanoribbons and WSe2 nanoribbons yields the one-dimensional WS2 / WSe2 heterojunction material. The growth temperature is 800℃~1150℃. The growth time for each component supplied by the sequentially switched WS2 source and WSe2 source is 1-3 min. The protective atmosphere and reducing atmosphere are a mixture of Ar, H2 and H2O or a mixture of N2, H2 and H2O, with a flow rate of 10~200 sccm.

[0034] In some embodiments, in step S2, when the WS2 source is placed in the central heating zone of the tubular furnace, the heating time is 3 to 10 minutes, and when the WSe2 source is placed in the central heating zone of the tubular furnace, the heating time is 1 to 3 minutes.

[0035] In some embodiments, the substrate is a SiO2 / Si, sapphire, or mica substrate.

[0036] This specific embodiment also proposes the application of the above-mentioned one-dimensional WS2 / WSe2 heterojunction material or the one-dimensional WS2 / WSe2 heterojunction material prepared by the above preparation method in field-effect transistors, light-emitting devices, photodetectors, flexible electronic devices or nano-integrated devices.

[0037] Beneficial effects also include: 1) Periodic alternating growth of monolayer WS2 and monolayer WSe2 components is achieved in the width direction of one-dimensional nanoribbons to form a one-dimensional multi-interface heterojunction superlattice structure.

[0038] 2) Compared to the intrinsic planar properties of two-dimensional semiconductors, the one-dimensional superlattice of the present invention concentrates the component modulation in a single one-dimensional nanostructure, which can achieve fine control of component length, period number and interface quality at a smaller feature size, and is more suitable for constructing micro-nano scale functional units.

[0039] 3) One-dimensional structures have natural directional transport channels, and the carrier transport paths are more concentrated, which can reduce the adverse effects of lateral diffusion, random scattering and multi-path transport in two-dimensional planar structures, thereby helping to improve carrier transport efficiency and photoelectric conversion efficiency.

[0040] 4) One-dimensional nanoribbon structures facilitate bridging electrodes, array arrangement, and high-density integration, making them suitable for applications in field-effect transistors, light-emitting devices, photodetectors, flexible electronic devices, and nano-integrated devices.

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] In this invention, the terms "some embodiments," "this embodiment," and examples are used to describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0043] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0044] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0045] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0046] Example 1 Preparation of one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials: This embodiment proposes a one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial, which is prepared by the following steps: like Figure 1As shown, WS2 powder and WSe2 powder are placed inside the quartz tube of the tube furnace 2, with WS2 powder 5 placed in the central heating zone of the tube furnace and WSe2 powder 6 placed upstream away from the central heating zone. The containers holding the two precursor powders are connected by a quartz rod 4 and a magnet 1, respectively, so that the precursor powders can move axially inside the quartz tube and can enter or exit the central heating zone under the action of an external magnetic field.

[0047] The SiO2 / Si substrate 3, which was spin-coated with a 6% NaCl solution and dried, was placed in the downstream deposition zone (i.e., nucleation growth zone) of the tube furnace. The downstream deposition zone was located at one end near the gas outlet, about 10 cm away from the central heating zone of the tube furnace.

[0048] Subsequently, a mixed carrier gas consisting of high-purity Ar, H2, and H2O was introduced into the quartz tube of the tubular furnace, with the ratios of Ar, H2, and H2O being 90%, 5%, and 5%, respectively. This gas flow was continued for approximately 2 hours to remove residual air from the quartz tube. Afterward, a heating program was initiated, with a heating rate of 50°C / min, raising the temperature of the central heating zone to 950°C–1150°C. The downstream deposition zone temperature was controlled at 600°C–750°C and held for 3 minutes, resulting in the initial growth of one-dimensional WS2 single-component nanoribbons (i.e., WS2 nanoribbons) on the substrate surface.

[0049] After the WS2 nanoribbon growth is completed, a quartz boat containing WSe2 precursor powder is rapidly pushed into the central heating zone by an external magnet, while the WS2 precursor powder is moved out of the central heating zone. The substrate position is kept unchanged, and the temperature of the central heating zone is set to 950 ℃~1050 ℃, and the temperature of the downstream deposition zone is set to 600 ℃~700 ℃. The temperature is maintained for 3 min, allowing WSe2 to continue to grow epitaxially on the already formed one-dimensional WS2 nanoribbon to form a WSe2 nanoribbon, thus forming a one-dimensional WS2 / WSe2 heterojunction nanoribbon.

[0050] The supply of WS2 and WSe2 source powders was alternately switched three times in the above manner, with each holding time lasting 1 minute. This alternating control of the two precursors entering the central heating zone and undergoing deposition growth resulted in a superlattice structure on the same one-dimensional nanoribbon, composed of periodically alternating WS2 and WSe2 components. The width of each component and the overall periodic structure within the formed superlattice could be controlled by adjusting the holding time and the number of switching cycles at each stage. After growth was complete, heating was stopped, and the system was allowed to cool naturally to room temperature before the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial was removed.

[0051] Optical micrographs of the obtained samples are as follows Figure 2As shown, due to the differences in composition and optical contrast between WS2 and WSe2, the obtained one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials exhibit a banded structure with periodic alternating distribution along the one-dimensional extension direction.

[0052] The obtained samples were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and photoluminescence spectroscopy (PL). The results are as follows: Figure 3 , Figure 4 and Figure 5 As shown in the transmission electron microscope (TEM) images, the one-dimensional WS2 / WSe2 heterojunction superlattice exhibits an alternating light and dark one-dimensional banded structure with high crystal quality. The superlattice interface 7 has an atomically steep profile. The spatial distribution mapping diagram shows that W is uniformly distributed in the superlattice nanoribbons, while S and Se are alternately distributed. Line scan spectra along the width of the nanoribbons also confirm this result.

[0053] Raman spectroscopy characterization results show that the one-dimensional superlattice nanoribbons contain two characteristic peaks E of WS2. 2g (354cm) -1 ) and A 1g (419 cm) -1 ), and the characteristic peak A of WSe2 1g (251cm) -1 The characteristic peaks of each material component are consistent with the reported data and also exhibit a periodic alternating distribution. The photoluminescence spectrum results show that the heterojunction superlattice contains PL peaks of both WS2 and WSe2. The additional peak at 835 nm originates from the interlayer exciton peaks of the heterojunction superlattice. These results demonstrate that the synthesized one-dimensional WS2 / WSe2 heterojunction superlattice has high quality, and that WS2 and WSe2 retain their intrinsic crystal and optical properties as the dimensionality decreases.

[0054] The above results indicate that the sample prepared in this embodiment is a one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial with a clear interface, periodically alternating components, and high crystallinity.

[0055] Example 2 This embodiment keeps the growth apparatus, precursor type, substrate type and basic growth process as described in Example 1 unchanged. By adjusting the growth time of each stage of WS2 and WSe2 and the number of alternating reactions, the component width and period number of the obtained one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial are controlled.

[0056] During the growth of the WSe2 component, the growth times were controlled at 0 min, 1 min, 2 min, and 3 min, while other conditions remained constant. Scanning electron microscope images of the obtained samples are shown below. Figure 6 As shown in the figure, the results indicate that when the WSe2 growth times are 0 min, 1 min, 2 min, and 3 min, the corresponding widths of the formed WSe2 components are approximately 0, 400 nm, 2 μm, and 3 μm, respectively. This result demonstrates that the width of individual components in the superlattice can be effectively controlled by adjusting the precursor supply time at different stages.

[0057] Furthermore, shortening the single growth time of the WSe2 component to 3 s results in a corresponding decrease in the width of a single WS2 or WSe2 component, thereby increasing the heterojunction period density per unit width. Increasing the number of precursor alternations to 7 times can correspondingly increase the number of heterojunction interfaces in a single one-dimensional nanoribbon, thus obtaining one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials with more periods, such as... Figure 6 As shown in e, the narrowest single-component width in the heterojunction superlattice is approximately 14 nm.

[0058] Furthermore, by adjusting the carrier gas flow rate and growth temperature, the transport rate of the precursor in the reaction zone and the reaction kinetics on the substrate surface can be further altered, thereby affecting the growth rate of the nanostructure, the component segment size, and the clarity of the heterojunction interface. This demonstrates that the method described in this invention not only enables the preparation of one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials but also allows for controllable adjustment of their structural parameters, exhibiting good repeatability and tunability.

[0059] Example 3 This embodiment proposes a one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial, which is prepared by the following steps: like Figure 1 As shown, WS2 powder and WSe2 powder are placed inside the quartz tube of a tubular furnace, with the WS2 powder placed in the central heating zone and the WSe2 powder placed upstream away from the central heating zone. The containers holding the two precursor powders are connected by a quartz rod and a magnet, allowing the precursor powders to move axially within the quartz tube and enter or exit the central heating zone under the influence of an external magnetic field.

[0060] A SiO2 / Si substrate coated with a 6% KCl solution and dried was placed in the downstream deposition zone (i.e., nucleation growth zone) of a tube furnace. The downstream deposition zone is located at the end near the gas outlet, about 10 cm away from the central heating zone of the tube furnace.

[0061] Subsequently, a mixed carrier gas consisting of high-purity Ar, H2, and H2O was introduced into the quartz tube of the tubular furnace, with the ratios of Ar, H2, and H2O being 90%, 5%, and 5%, respectively. This gas flow was continued for approximately 2 hours to remove residual air from the quartz tube. Afterward, a heating program was initiated, with a heating rate of 50°C / min, raising the temperature of the central heating zone to 800°C–1100°C. The downstream deposition zone temperature was controlled at 600°C–750°C and held for 3 minutes, resulting in the initial growth of one-dimensional WS2 single-component nanoribbons (i.e., WS2 nanoribbons) on the substrate surface.

[0062] After the WS2 nanoribbon growth is completed, a quartz boat containing WSe2 precursor powder is pushed into the central heating zone by an external magnet, while the WS2 precursor powder is moved out of the central heating zone. The substrate position is kept unchanged, and the temperature of the central heating zone is set to 950 ℃~1050 ℃, and the temperature of the downstream deposition zone is set to 600 ℃~700 ℃. The temperature is maintained for 3 min, so that WSe2 continues to grow epitaxially on the already formed one-dimensional WS2 nanoribbon to form a WSe2 nanoribbon, thereby forming a one-dimensional WS2 / WSe2 heterojunction nanoribbon.

[0063] The supply of WS2 and WSe2 source powders is alternately switched six times in a periodic manner, that is, the two precursors are alternately controlled to enter the central heating zone and undergo deposition growth, forming a superlattice structure composed of periodically alternating WS2 and WSe2 components on the same one-dimensional nanoribbon. The width of each component in the formed superlattice and the overall periodic structure can be controlled by the holding time and the number of switching times in the corresponding stages. After the growth is completed, heating is stopped, the system is allowed to cool naturally to room temperature, and the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial is taken out.

[0064] Example 4 This embodiment proposes a one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial, which is prepared by the following steps: like Figure 1 As shown, WS2 powder and WSe2 powder are placed inside the quartz tube of a tubular furnace, with the WS2 powder placed in the central heating zone and the WSe2 powder placed upstream away from the central heating zone. The containers holding the two precursor powders are connected by a quartz rod and a magnet, allowing the precursor powders to move axially within the quartz tube and enter or exit the central heating zone under the influence of an external magnetic field.

[0065] A SiO2 / Si substrate, which has been spin-coated with a 6% NaI solution and dried, is placed in the downstream deposition zone (i.e., nucleation growth zone) of a tube furnace. The downstream deposition zone is located at one end near the gas outlet, about 10 cm away from the central heating zone of the tube furnace.

[0066] Subsequently, a mixed carrier gas consisting of high-purity Ar, H2, and H2O was introduced into the quartz tube of the tubular furnace, with the ratios of Ar, H2, and H2O being 90%, 5%, and 5%, respectively. This gas flow was continued for approximately 2 hours to remove residual air from the quartz tube. Afterward, a heating program was initiated, with a heating rate of 50°C / min, raising the temperature of the central heating zone to 800°C–1100°C. The downstream deposition zone temperature was controlled at 600°C–750°C and held for 5 minutes, resulting in the initial growth of one-dimensional WS2 single-component nanoribbons (i.e., WS2 nanoribbons) on the substrate surface.

[0067] After the WS2 nanoribbon growth is completed, a quartz boat containing WSe2 precursor powder is pushed into the central heating zone by an external magnet, while the WS2 precursor powder is moved out of the central heating zone. The substrate position is kept unchanged, and the temperature of the central heating zone is set to 950 ℃~1050 ℃, and the temperature of the downstream deposition zone is set to 600 ℃~700 ℃. The temperature is maintained for 2 min, so that WSe2 continues to grow epitaxially on the already formed one-dimensional WS2 nanoribbon to form a WSe2 nanoribbon, thereby forming a one-dimensional WS2 / WSe2 heterojunction nanoribbon.

[0068] The supply of WS2 and WSe2 source powders was alternately switched five times in a periodic manner, i.e., the two precursors were alternately controlled to enter the central heating zone and undergo deposition growth, forming a superlattice structure composed of periodically alternating WS2 and WSe2 components on the same one-dimensional nanoribbon. The width of each component in the formed superlattice and the overall periodic structure can be controlled by the holding time and the number of switching times in the corresponding stages. After growth was completed, heating was stopped, and the system was allowed to cool naturally to room temperature before the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial was removed.

[0069] Comparative Example 1 The difference between this comparative example and Example 1 is that WSe2 powder was not used; instead, an equal amount of WS2 powder as in Example 1 was used. All other process conditions were the same as in Example 1. The resulting material was a one-dimensional, single-component WS2 nanoribbon material, as shown in the results. Figure 7 As shown.

[0070] Comparative Example 2 The difference between this comparative example and Example 1 is that NaCl or other salt halide solutions were not spin-coated onto the SiO2 / Si substrate. All other raw materials and process steps were the same as in Example 1, resulting in two-dimensional WS2 / WSe2 heterojunction nanosheets. The results are as follows: Figure 8 As shown.

[0071] Example 5 The one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials prepared in Examples 1, 2, and 3 were transferred onto a SiO2 / Si substrate with an insulating layer. Electrodes were then fabricated at both ends of the heterojunction superlattice nanoribbons using an electron beam lithography combined with metal evaporation method (from existing technology), thus constructing a photodetector device based on the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials. Electrode materials can be Ti / Au, Cr / Au, or other commonly used electrode materials in the art; specifically, Cr / Au (10 / 50 nm) was used as the contact electrode.

[0072] The current-voltage (IV) characteristics of devices with different structures under 450 nm wavelength laser irradiation conditions were tested under vacuum and room temperature conditions. Figure 9 As shown, the test results indicate that the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial exhibits a significantly enhanced photocurrent response under illumination compared to one-dimensional single-component WS2 nanoribbons and two-dimensional WS2 / WSe2 heterojunction nanosheets. Compared to the one-dimensional WS2 nanoribbon material of Comparative Example 1 and the two-dimensional planar WS2 / WSe2 heterojunction nanosheets of Comparative Example 2, the device constructed in Example 1 of this invention exhibits superior photoelectric conversion characteristics. The photocurrent of the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial prepared in Example 1 is more than 6 times that of the pure WS2 nanoribbon of Comparative Example 1, and the photocurrent of the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial prepared in Example 1 is more than 2.5 times that of the two-dimensional WS2 / WSe2 heterojunction nanosheets of Comparative Example 2, with a linearity far superior to the two-dimensional structure. This demonstrates that the one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterial prepared in Example 1 can significantly improve the photoelectric response and exhibit superior photoelectric performance. This is mainly attributed to the fact that the WS2 and WSe2 components, arranged periodically and alternately along the nanoribbon direction in the one-dimensional superlattice structure prepared in this invention, form multiple heterojunction interfaces, which can form continuous periodic performance band modulation in the one-dimensional direction. This enhances the separation and directional transport of photogenerated carriers, reduces the carrier recombination probability, and improves the photoelectric conversion efficiency of the device. At the same time, the one-dimensional structure is beneficial for the bridging and array integration of device electrodes, showing superior directional transport and device application potential compared to two-dimensional planar heterojunction superlattice materials.

[0073] In summary, the alternating source growth method of this invention can control the component width and the number of heterojunction interfaces in one-dimensional WS2 / WSe2 heterojunction superlattice nanomaterials, thereby achieving controllable fabrication of the target one-dimensional superlattice structure. The one-dimensional WS2 / WSe2 heterojunction superlattice photodetector constructed based on this invention exhibits excellent photoelectric detection performance.

[0074] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a one-dimensional WS2 / WSe2 heterojunction material, characterized in that, Includes the following steps: S1. Arrange the WS2 source and WSe2 source in predetermined positions within the reaction apparatus, and place the growth substrate loaded with salt halides in the nucleation growth region; S2. Under a protective atmosphere and a reducing atmosphere, the temperature is raised to the growth temperature, so that the WS2 source and the WSe2 source react sequentially. By switching the effective supply of the WS2 source and the WSe2 source in a time sequence, and with the catalytic induction of salt halides, the WS2 component and the WSe2 component are alternately epitaxially grown in the width direction of the one-dimensional nanoribbon to form the corresponding WS2 nanoribbon and WSe2 nanoribbon. The alternating arrangement of the WS2 nanoribbon and the WSe2 nanoribbon results in the one-dimensional WS2 / WSe2 heterojunction material. In step S1, the salt halide is one or more of KCl, NaCl, KI and NaI; The heterojunction material is a one-dimensional structure material composed of WS2 nanoribbons and WSe2 nanoribbons arranged alternately along the width direction. The WS2 nanoribbons and WSe2 nanoribbons are grown in an alternating arrangement to form multiple periodic heterojunction interfaces.

2. The method for preparing a one-dimensional WS2 / WSe2 heterojunction material according to claim 1, characterized in that, In step S2, the growth temperature is 800℃~1150℃; and / or, in step S2, the single-component growth time supplied by the timing-switched WS2 source and WSe2 source is 1~3 min.

3. The method for preparing a one-dimensional WS2 / WSe2 heterojunction material according to claim 1, characterized in that, In step S2, the protective atmosphere and reducing atmosphere are a mixture of Ar, H2 and H2O or a mixture of N2, H2 and H2O, and the flow rate of the mixture is 10 to 200 sccm.

4. The method for preparing a one-dimensional WS2 / WSe2 heterojunction material according to claim 1, characterized in that, In step S1, the reaction device is a tubular furnace quartz tube; in step S2, when the WS2 source is placed in the central heating zone of the tubular furnace, the heating time is 3 to 10 minutes, and when the WSe2 source is placed in the central heating zone of the tubular furnace, the heating time is 1 to 3 minutes.

5. The method for preparing a one-dimensional WS2 / WSe2 heterojunction material according to claim 1, characterized in that, The one-dimensional WS2 / WSe2 heterojunction material has a length of 5–100 μm, a width of 1–20 μm, and a period number of 1–10, wherein the width of a single component nanoribbon is 14 nm–5 μm.

6. The method for preparing a one-dimensional WS2 / WSe2 heterojunction material according to claim 1, characterized in that, The heterojunction interface is an atomically steep heterojunction interface.

7. The application of the one-dimensional WS2 / WSe2 heterojunction material prepared by the preparation method according to any one of claims 1-6 in field-effect transistors, light-emitting devices, photodetectors, flexible electronic devices or nano-integrated devices.

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