Two-dimensional layered nanosheet, thin film, growth method of two-dimensional layered nanosheet and thin film, and preparation of photoelectric device

Abstract

The invention relates to a preparation method of a two-dimensional layered nanosheet and film and a photoelectric device of the two-dimensional layered nanosheet and film. According to the preparation method, a vacuum environment is adopted in the material growing process, and inert gas does not need to serve as carrier gas; large-size atomic crystals, a large-area film and an alloy film thereof are generated by adjusting the dosage of In2Se3 and In2S3 powder, the distance between the In2Se3 and In2S3 powder and the fluorophlogopite sheet, the reaction time and the reaction temperature of the In2Se3 and In2S3 powder and the fluorophlogopite sheet; the method has the advantages of simple growth process, high implementation feasibility, environmental protection and the like; the alpha-In2Se3 prepared by the method can be transferred to different substrates through a simple and lossless transfer method, and the prepared photoelectric device has good light response sensitivity and can maintain relatively stable performance no matter under weak light or strong light.

Description

Technical Field

[0001] The present invention relates to the technical field of two-dimensional semiconductor materials, and in particular to a two-dimensional layered nanosheet, a thin film, a growth method thereof, and the preparation of a photoelectric device. Background Art

[0002] Based on III A -IV A A family of two-dimensional (2D) semiconductor materials has been successfully used as a substitute for silicon in many electronic and optoelectronic applications and used to fabricate flexible, transparent, and novel structural optoelectronic devices. Layered semiconductor α-In2Se3 has attracted increasing interest. On the one hand, unlike the indirect bandgap properties of transition metal sulfides, multilayer α-In2Se3 has a direct bandgap, high absorption coefficient, and electron mobility, and has been applied to high-performance photodetectors from ultraviolet to near-infrared, with broad application prospects. On the other hand, unlike black phosphorus, which is also a 2D material with a direct bandgap, two-dimensional α-In2Se3 is very stable in air, which is very important for practical applications.

[0003] At present, the preparation methods of α-In2Se3 mainly include mechanical exfoliation, chemical vapor deposition (CVD) and physical vapor deposition (PVD). Some layered α-In2Se3 nanosheets obtained by the exfoliation method lack controllability in terms of uniformity, size and thickness. In CVD and PVD, the precursor powder is mostly placed upstream of the reactor, and the substrate is placed downstream of the reactor. In addition to the high reaction temperature and the use of inert gas as a protective gas or carrier gas, the size of the two-dimensional material grown is generally small, which is not conducive to the production of optoelectronic devices. In addition, the composition control of alloy materials can greatly improve the flexibility of optoelectronic device design, but there are few related studies on the growth of α-In2Se3 alloys. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the primary purpose of the present invention is to provide a two-dimensional layered nanosheet, a thin film and a growth method thereof and a preparation of an optoelectronic device. The growth method is carried out in a vacuum environment, is green and environmentally friendly, and the prepared In2Se3 nanosheets, In2S3 nanosheets, In2Se 3(1-x) S 3x The size of the alloy nanosheets exceeds 100 microns, and the size of the obtained thin films is up to the millimeter level, achieving the growth of large-size, high-quality two-dimensional material layers. The prepared photodetector has excellent light response sensitivity and good stability.

[0005] In one aspect, the present invention provides a method for growing two-dimensional layered nanosheets and thin films, comprising the following steps:

[0006] Place an appropriate amount of at least one source powder of In2Se3 and In2S3 at the bottom of a quartz boat in a horizontal tube furnace quartz tube, and place a freshly cracked fluorphlogopite sheet obliquely above the source powder, with the freshly cracked side facing the source powder;

[0007] The horizontal tube furnace is sealed, and then a large flow of inert gas is introduced for inflation for a certain period of time, followed by vacuum treatment, and then the central constant temperature zone of the horizontal tube furnace is heated to a target temperature at a certain heating rate. When the central constant temperature zone reaches the target temperature, the quartz tube is quickly moved to the central constant temperature zone for insulation for a certain period of time, and then the quartz tube is quickly moved out of the central constant temperature zone and cooled to room temperature with the furnace to obtain a two-dimensional layered In2Se3 nanosheet / film, In2S3 nanosheet / film or In2Se 3(1-x) S 3x Alloy nanosheets, wherein 0<x<1.

[0008] Furthermore, the target temperature is 700-850°C.

[0009] Furthermore, the heating rate is 20-30°C / min.

[0010] Furthermore, the insulation time is 5 minutes to 20 minutes.

[0011] Furthermore, the vertical distance between the mica sheet and the quartz boat is 5 mm to 20 mm;

[0012] In the gas filling step, the large flow rate of the inert gas is 100 to 200 sccm, and the gas filling time is 0.2 to 0.5 h.

[0013] On the one hand, the present invention also provides a two-dimensional layered nanosheet and film obtained by the above growth method.

[0014] Furthermore, the lateral size of the two-dimensional layered nanosheets and thin films is 10 μm to 1 mm.

[0015] In one aspect, the present invention also provides a method for preparing a photoelectric device, comprising the following steps:

[0016] A mixed solution of polystyrene and toluene is spin-coated on the surface of the substrate with the above-mentioned two-dimensional layered nanosheets and thin films attached thereto, and a PS film is formed after heating. After cooling, the substrate is placed in deionized water, and the PS film is slowly separated from the substrate. The PS film is suspended in deionized water, and then the suspended PS film is transferred to a Si / SiO2 target substrate, the target substrate is heated, and then the PS film is dissolved with a toluene solution, and after drying with a nitrogen gun, a two-dimensional layered material layer is obtained on the target substrate;

[0017] Electrodes are then fabricated on the two-dimensional layered material layer.

[0018] Further, in the step of forming a PS film after heating, the heating temperature is 90° C. to 100° C., and the heating time is 4 to 10 minutes;

[0019] Further, in the step of heating the target substrate, the heating temperature is 100° C. to 150° C., and the heating time is 10 to 30 minutes;

[0020] In one aspect, the present invention further provides a photoelectric device, which is prepared by using the above-mentioned method for preparing a photoelectric device.

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

[0022] The method for growing two-dimensional layered nanosheets and thin films of the present invention adopts a vacuum environment during the growth of the material layer, does not require an inert gas as a carrier gas, has the characteristics of being green and environmentally friendly, having no polluting gas discharge, and having simple preparation steps, and the method obtains high-quality, large-sized two-dimensional layered In2Se3 nanosheets / thin films, In2S3 nanosheets / thin films and In2Se 3(1-x) S 3x Alloy nanosheets, the maximum lateral size of the nanosheets exceeds 100 microns, and the lateral size of the film can reach up to millimeter level.

[0023] On the other hand, this growth method can obtain single crystal nanosheets, polycrystalline nanosheets or films, as well as nanosheets or films of different sizes by adjusting the amount of source powder, the distance between the mica sheet and the quartz boat, the target temperature and the insulation time. The growth method is simple and controllable.

[0024] On the other hand, the present invention uses the two-dimensional layered nanosheets or thin films grown to prepare optoelectronic devices, which have good light response sensitivity and stability. For example, the optoelectronic device made of the grown α-In2Se3 nanosheets was tested for switching characteristics under 405nm laser irradiation. As the optical power density increases from 0.07 to 37mW / cm 2 The photoelectric detection device has good light response sensitivity. In addition, it can maintain relatively stable performance regardless of weak light or strong light. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a growth device for a two-dimensional layered α-In2Se3 thin film according to an embodiment of the present invention;

[0026] Figure 2 This is an optical microscope image of a two-dimensional layered α-In2Se3 thin film grown in Example 1 of the present invention;

[0027] Figure 3This is a Raman spectrum of the two-dimensional layered α-In2Se3 film of Example 1 of the present invention;

[0028] Figure 4 This is an atomic force microscope image of a two-dimensional layered α-In2Se3 film grown in Example 2 of the present invention;

[0029] Figure 5 This is an optical microscope image of a two-dimensional layered α-In2Se3 thin film grown in Example 3 of the present invention;

[0030] Figure 6 The two-dimensional In2Se grown in Example 4 of the present invention 0.6 S 2.4 Optical microscope image of alloy nanosheets;

[0031] Figure 7 This is a microscope image of the In2Se3 photoelectric device prepared in Example 5 of the present invention;

[0032] Figure 8 The photoelectric device prepared in Example 5 of the present invention is used as a photodetector to measure the photocurrent characteristics and switching characteristics. DETAILED DESCRIPTION

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention. The experimental methods described in the following embodiments are all conventional methods unless otherwise specified; the reagents and materials, unless otherwise specified, can be obtained from public commercial channels.

[0034] Spatially relative terms such as "below," "beneath," "below," "above," "upper," etc. are used in this specification to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures.

[0035] The α-In2Se3 powder used in the present invention is purchased from Aladdin, and the purity is 99.99%. The lateral dimension refers to the dimension in the plane where the film or nanosheet is located.

[0036] The embodiment of the present invention provides a method for preparing a two-dimensional α-In2Se3 thin film and alloy nanosheet without the need for protective gas and pollution gas exhaust, and using a quartz tube as a vacuum reaction chamber comprises the following steps:

[0037] (1) Prepare a quartz boat with a length of about 50-60 mm and a width of about 10-20 mm, and evenly spread the weighed In2Se3 powder (or In2Se3 and In2S3 powders in different proportions) on the bottom of the quartz boat.

[0038] (2) Place a 10-20 mm long and wide fluorphlogopite mica sheet obliquely on top of the quartz boat, with the freshly peeled surface facing the powder. The vertical distance between the mica sheet and the In2Se3 (In2Se3 and In2S3 mixed powder) powder is about 5-20 mm.

[0039] (3) The quartz boat containing the mica flakes and the powder source is placed in the target area of ​​the horizontal tube furnace, wherein the target area of ​​the quartz tube of the horizontal tube furnace is about 20-25 mm in outer diameter, 16-21 mm in inner diameter, and about 500-800 mm in length.

[0040] (4) After the quartz boat is placed, seal the tube furnace. Open the inlet and outlet valves at both ends of the quartz tube and introduce 100-200 sccm of inert gas or nitrogen to ensure the dryness of the quartz tube and remove excess air. This process takes 0.2-0.5 hours. Then close the inlet and outlet valves at both ends.

[0041] (5) Open the exhaust valve and evacuate the horizontal tube furnace by a mechanical pump for 0.5 to 2 hours. Then heat the central constant temperature zone of the horizontal tube furnace to 700 to 850°C at a heating rate of 20 to 30°C / min. When the temperature of the central constant temperature zone of the horizontal tube furnace reaches the target temperature and stabilizes, the horizontal moving slide quickly moves the central constant temperature zone of the tube furnace to the target area where the quartz boat is located. Maintain a constant temperature for 0.5 to 20 minutes to grow two-dimensional layered α-In2Se3 thin films and alloy nanosheets.

[0042] (6) When the reaction is completed, the slide rail furnace is quickly moved to move the heating source out of the target area to achieve a rapid cooling effect.

[0043] Another object of the present invention is to provide a method for preparing an optoelectronic device based on the nanosheets and thin films obtained by the above growth, comprising the following steps:

[0044] A drop of polystyrene (PS) toluene solution was spin-coated on the surface of the two-dimensional layered α-In2Se3 nanosheet grown above, so that the PS solution was evenly spread on the mica sheet. The mica sheet was then placed on an electric heating plate and heated at 90-100°C for 4-10 minutes to form a PS film.

[0045] Next, after it cools to room temperature, pick up the PS film at the edge of the mica sheet, and use a rubber-tipped dropper to drop 5 to 10 drops of deionized water. The water droplets will slowly penetrate into the interface between the material and the mica sheet, and finally the deionized water completely infiltrates the mica sheet, so that the α-In2Se3 nanosheets are separated from the substrate along with the PS film. The PS film is suspended in deionized water, with the PS film facing up and the two-dimensional layered α-In2Se3 nanosheets facing down. Then use a clean target substrate, such as a Si / SiO2 substrate, to pick up the PS film. Then place the Si / SiO2 substrate on an electric heating plate and bake it at 100 to 150°C for 10 to 30 minutes to remove excess water, so that the PS film is in close contact with the substrate.

[0046] Finally, the PS film was dissolved with toluene solution, and the excess toluene solution was quickly blown dry with a nitrogen gun, thereby realizing the transfer of the two-dimensional layered α-In2Se3 from the fluorophlogopite substrate to the Si / SiO2 substrate.

[0047] The Si / SiO2 substrate with two-dimensional layered α-In2Se3 nanosheets was placed on a coating machine, and photoresist was spin-coated at 1500-5000rpm and 60s, and heated at 100-120℃ for 4-10min. After mask alignment, photolithography, development and other steps, metal electrodes were thermally evaporated onto the Si / SiO2 substrate, and after repeated acetone washing, a photoelectric device with electrodes was obtained. The test results show that the photoelectric device exhibits good photoelectric response under 405nm laser irradiation.

[0048] Example 1

[0049] This embodiment is used to prepare a two-dimensional layered α-In2Se3 thin film, including the following steps:

[0050] 1) Before the experiment, clean the quartz boat and quartz tube used. Spread 150-200 mg of In2Se3 powder material evenly on the bottom of the quartz boat. Place the freshly cracked side of the mica sheet toward the In2Se3 powder to ensure that the epitaxial growth surface is smooth and dust-free. Place the mica sheet obliquely above the quartz boat containing In2Se3 powder, with the vertical distance ranging from 5mm to 20mm.

[0051] 2) Place the quartz boat into the target area of ​​the quartz tube of the PVD equipment, seal the tube furnace, open the inlet and outlet valves at both ends of the quartz tube, introduce 100-200 sccm of inert gas, the inert gas includes nitrogen, and then perform vacuum treatment.

[0052] 3) Then the temperature of the central constant temperature zone of the horizontal tube furnace is raised to 850°C at a rate of 25°C / min. When the temperature of the central constant temperature zone of the horizontal tube furnace reaches 850°C and stabilizes, the slide is moved horizontally to quickly move the target area along with the quartz tube to the central constant temperature zone of the horizontal tube furnace and keep the temperature constant for 20 minutes to grow the two-dimensional layered α-In2Se3 film.

[0053] After the holding time is over, the target area is quickly moved out of the central constant temperature zone, the growth process is over, and the heater is turned off until the temperature of the tube furnace drops to room temperature. At the same time, the slide rail is quickly moved to move the heating source out of the target area to achieve a rapid cooling effect. Figure 1 shown. Figure 2 This is an optical micrograph of the α-In2Se3 thin film grown at different vertical distances between the mica sheet and the In2Se3 powder in Example 1, where the arrows indicate a direction where the vertical distance gradually increases. This indicates that by adjusting the distance between the mica sheet and the powder source under the condition of maintaining the growth temperature at 850°C for 20 minutes, the controllable growth of In2Se3 thin films and triangular-shaped In2Se3 single crystal nanosheets can be achieved. Figure 3 The Raman spectrum of the two-dimensional In2Se3 film prepared in Example 1 shows that α-In2Se3 exhibits three vibration modes, which is consistent with previous studies and indicates that the grown α-In2Se3 is in the α phase and has high quality.

[0054] Example 2

[0055] This embodiment prepares two-dimensional layered α-In2Se3 films of different thicknesses, including the following steps:

[0056] 1) Before the experiment, clean the quartz boat and quartz tube used. Spread 150-200 mg of In2Se3 powder material evenly on the bottom of the quartz boat. Place the freshly cracked side of the mica sheet toward the In2Se3 powder to ensure that the epitaxial growth surface is smooth and dust-free. The vertical distance between the mica sheet and the powder is selected to be 10 mm.

[0057] 2) Place the quartz boat into the target area of ​​the quartz tube of the PVD equipment, seal the tube furnace, open the inlet and outlet valves at both ends of the quartz tube, introduce 100-200 sccm of inert gas, the inert gas includes nitrogen, and then perform vacuum treatment.

[0058] 3) Then the temperature of the central constant temperature zone of the horizontal tube furnace is raised to 700-850°C at a rate of 25°C / min. When the temperature of the central constant temperature zone of the horizontal tube furnace reaches the target temperature and stabilizes, the slide is moved horizontally to quickly move the target area to the central constant temperature zone of the horizontal tube furnace along with the quartz tube, and the temperature is maintained for 5 minutes to grow the two-dimensional layered α-In2Se3 film.

[0059] 4) After the insulation time is over, the target area is quickly moved out of the central constant temperature zone, the growth process is over, and the heater is turned off until the temperature of the tube furnace drops to room temperature. Quickly move the slide rail to move the heating source out of the target area to achieve a rapid cooling effect. Figure 4 The AFM characterization images of the α-In2Se3 thin films obtained at heating temperatures of 700, 750, and 850°C in Example 2 show that the thickness of the film increases with increasing temperature, indicating that by adjusting the heating temperature under the condition of keeping the temperature for 5 minutes, the triangular In2Se3 nanosheets with different thicknesses can be grown in a controllable manner.

[0060] Example 3

[0061] This embodiment achieves the preparation of two-dimensional layered α-In2Se3 nanosheets of different lateral sizes by adjusting the holding time, including the following steps:

[0062] 1) Before the experiment, clean the quartz boat and quartz tube used. Place the mica sheet with the freshly cracked side facing the In2Se3 powder to ensure that the epitaxial growth surface is smooth and dust-free. Place the mica sheet obliquely on the quartz boat containing In2Se3 powder, with a vertical distance of 10 mm.

[0063] 2) Place the quartz boat into the target area of ​​the quartz tube of the PVD equipment, seal the tube furnace, open the inlet and outlet valves at both ends of the quartz tube, introduce 100-200 sccm of inert gas or nitrogen, and then perform vacuum treatment.

[0064] 3) Then the central constant temperature zone of the horizontal tube furnace is heated to 750°C at a rate of 25°C / min. When the temperature of the central constant temperature zone of the horizontal tube furnace reaches the target temperature and stabilizes, the slide is moved horizontally to quickly move the target area along with the quartz tube to the central constant temperature zone of the horizontal tube furnace and keep the temperature constant for 5-10 minutes to grow the two-dimensional layered α-In2Se3 film.

[0065] 4) After the insulation time is over, the target area is quickly moved out of the central constant temperature zone, the growth process is over, and the heater is turned off until the temperature of the tube furnace drops to room temperature. Quickly move the slide rail to move the heating source out of the target area to achieve a rapid cooling effect. Figure 5 The optical micrographs of the α-In2Se3 thin films obtained with the holding time of 5min and 10min in Example 3 are shown in FIG. As can be seen from the figure, with the increase of the holding time, the lateral size of the film also increases, and the maximum size can reach 100 microns. This indicates that under the condition of 750°C, by adjusting the holding time, the triangular morphology of In2Se3 nanosheets with different lateral sizes can be controlled to grow.

[0066] Example 4

[0067] This embodiment is used to prepare two-dimensional In2Se3 alloy nanosheets, including the following steps:

[0068] 1) Before the experiment, clean the quartz boat, quartz tube and other instruments used. Weigh a mixed powder of In2Se3 and In2S3 with a total mass of 300 mg. The stoichiometric ratio of In2Se3 and In2S3 is 1:4, and mix the powders thoroughly. Spread the mixed powder evenly on the bottom of the quartz boat. Place a freshly cracked fluorphlogopite sheet obliquely on top of the mixed powder, with the freshly cracked side of the mica sheet facing the mixed powder to ensure that the epitaxial growth surface is smooth and dust-free. The vertical distance between the mica sheet and the powder is selected to be 10 mm.

[0069] 2) Place the quartz boat into the target area of ​​the quartz tube of the PVD equipment, seal the tube furnace, open the inlet and outlet valves at both ends of the quartz tube, introduce 100-200 sccm of inert gas or nitrogen, and then perform vacuum treatment.

[0070] 3) Then the central constant temperature zone of the horizontal tube furnace is heated to 700°C at a rate of 25°C / min. When the temperature of the central constant temperature zone of the horizontal tube furnace reaches the target temperature and stabilizes, the slide is moved horizontally to quickly move the target area to the central constant temperature zone of the horizontal tube furnace along with the quartz tube, and the constant temperature is maintained for 10 minutes to grow two-dimensional In2Se3 alloy nanosheets.

[0071] After the holding time is over, the target area is quickly moved out of the central constant temperature zone, the growth process is over, and the heater is turned off until the temperature of the tube furnace drops to room temperature. Quickly move the slide rail to move the heating source out of the target area to achieve a rapid cooling effect. Figure 6 is an optical micrograph of the grown alloy nanosheets. Figure 6 As can be seen in the figure, regular and dense triangular nanosheets are grown on the mica substrate. The alloy nanosheets are stoichiometrically In2Se 0.6 S 2.4 .

[0072] Example 5

[0073] This embodiment provides a method for preparing a photoelectric device, comprising the following steps:

[0074] (1) Spin-coat a layer of PS toluene solution on the surface of the two-dimensional layered In2Se3 nanosheets grown in Example 1, place them on an electric heating plate, and heat them at 100°C for 4-10 minutes to form a PS film. After cooling to room temperature, PS crack the edge of the mica sheet, and use a rubber-tipped dropper to drip 2-3 drops of deionized water. Since the PS film layer with α-In2Se3 attached is hydrophobic and the mica sheet is hydrophilic, the water droplets will slowly penetrate into the interface between the material and the mica sheet, and finally the deionized water completely infiltrates the mica sheet, so that the α-In2Se3 nanosheet is separated from the substrate along with the PS.

[0075] (2) The PS film layer with α-In2Se3 attached is transferred to a petri dish filled with deionized water and suspended on the surface of the deionized water. At this time, the PS film is facing upward and the two-dimensional layered α-In2Se3 material is facing downward.

[0076] (3) Pick up the PS film with a Si / SiO2 substrate, place the Si / SiO2 substrate on a clean electric heating plate and bake it at 100-150°C for 10-30 minutes to remove excess water, so that the PS film is in close contact with the substrate. Finally, dissolve the PS film with a toluene solution, and quickly blow dry the excess toluene solution with a nitrogen gun, and the two-dimensional layered α-In2Se3 nanosheets are transferred from the mica substrate to the Si / SiO2 substrate.

[0077] (4) Then, a photoresist is spin-coated on the Si / SiO2 substrate with the two-dimensional layered α-In2Se3 attached, and the spin coating is performed at 1500-5000 rpm for 60 seconds, followed by heating at a temperature range of 100-120°C for 4-10 minutes. After exposure, the Si / SiO2 substrate is immersed in a developer for development, and finally the electrode pattern of the optoelectronic device is formed. Finally, the Ti / Au (10 / 60nm) electrode is evaporated by an electron beam evaporation coating device, and the optoelectronic device is finally obtained after repeated washing with acetone.

[0078] Figure 7 The optical micrograph of the two-dimensional layered α-In2Se3 photoelectric device prepared above is shown in Figure 2. The switching characteristics of the photoelectric device were tested under 405nm laser irradiation. Figure 8 As shown in Figure 2, as the optical power density increases from 0.07 to 37 mW / cm 2 The photoelectric detection device exhibits excellent light response sensitivity and can maintain relatively stable performance regardless of weak or strong light.

[0079] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for growing two-dimensional layered nanosheets and thin films, characterized in that: The following steps are involved: Place an appropriate amount of at least one source powder of In2Se3 and In2S3 at the bottom of the quartz boat in the quartz tube of the horizontal tube furnace, and place a freshly cracked fluorphlogopite sheet obliquely above the source powder, with the freshly cracked side facing the source powder; The horizontal tube furnace is sealed, and then a large flow of inert gas is introduced for inflation for a certain period of time, followed by vacuum treatment, and then the central constant temperature zone of the horizontal tube furnace is heated to a target temperature at a certain heating rate. When the central constant temperature zone reaches the target temperature, the quartz tube is quickly moved to the central constant temperature zone for insulation for a certain period of time, and then the quartz tube is quickly moved out of the central constant temperature zone and cooled to room temperature with the furnace to obtain a two-dimensional layered In2Se3 nanosheet / film, In2S3 nanosheet / film or In2Se 3(1-x) S 3x Alloy nanosheets, wherein 0<x<1.

2. The growth method according to claim 1, characterized in that The target temperature is 700-850°C.

3. The growth method according to claim 2, characterized in that: The vertical distance between the mica sheet and the quartz boat is 5 mm to 20 mm.

4. The growth method according to any one of claims 1 to 3, characterized in that: The insulation time is 5 to 20 minutes.

5. The growth method according to claim 4, characterized in that: The heating rate is 20-30°C / min; In the gas filling step, the large flow rate of the inert gas is 100 to 200 sccm, and the gas filling time is 0.2 to 0.5 h.

6. A two-dimensional layered nanosheet or film, characterized in that: Obtained by the growth method according to any one of claims 1 to 5.

7. A method for preparing a photoelectric device, characterized in that: The following steps are involved: A mixed solution of polystyrene and toluene is spin-coated on the surface of the substrate to which the two-dimensional layered nanosheets and thin films according to claim 6 are attached, and a PS film is formed after heating. After cooling, the substrate is placed in deionized water, and the PS film is slowly separated from the substrate. The PS film is suspended in deionized water, and then the suspended PS film is transferred to a target substrate, and the target substrate is heated. Then, the PS film is dissolved with a toluene solution, and dried with a nitrogen gun to obtain a two-dimensional layered material layer on the target substrate; Electrodes are then fabricated on the two-dimensional layered material layer.

8. The method for preparing a photoelectric device according to claim 7, characterized in that: The target substrate is a Si / SiO2 substrate; In the step of forming a PS film after heating, the heating temperature is 90° C. to 100° C., and the heating time is 4 to 10 minutes.

9. The method for preparing a photoelectric device according to claim 8, characterized in that: In the step of heating the target substrate, the heating temperature is 100° C. to 150° C. and the heating time is 10 to 30 minutes.

10. A photoelectric device, characterized in that: The photoelectric device is prepared by the method for preparing a photoelectric device according to claims 7 to 9.

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