A platinum diselenide and a preparation method and application thereof

Abstract

The application belongs to the technical field of two-dimensional thin film material growth and preparation, and discloses a kind of platinum diselenide and its preparation method and application, the morphology of the platinum diselenide is square single crystal, nanostructure with dendritic characteristics, sheet or continuous film.The application is innovative in morphology and product form, not only prepares platinum diselenide with square single crystal morphology, but also creates favorable conditions for fully exerting its potential different optoelectronic device applications, and can realize controllable preparation of square single crystal, nanostructure with dendritic characteristics, sheet and continuous film morphology through simple parameter adjustment.In terms of process compatibility, with low-temperature preparation process, the temperature limitation of traditional high-temperature method is effectively avoided, and the limitation of crystal domain size in traditional low-temperature method is broken through, and crystal lateral size meeting the actual application requirements can be obtained, providing a key guarantee for adaptation with existing processes.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of two-dimensional thin film material growth and preparation, and particularly relates to a platinum diselenide and a preparation method and application thereof. BACKGROUND

[0002] As a typical noble metal dichalcogenide, two-dimensional platinum diselenide (PtSe2) has unique layer number-dependent characteristics. Its band gap ranges from 0 to 1.2 eV, and it can change from semimetallic property to semiconducting property. The room-temperature carrier mobility of PtSe2 is up to 100 cm 2 / V·s or above, and it can maintain stable performance for a long time under atmospheric conditions. These excellent characteristics make PtSe2 show important application value in high-performance field effect transistors, mid-to-far infrared photodetectors (3-5 μm band), flexible electronic devices and other optoelectronic devices. Controlled preparation of PtSe2 single crystals with specific morphology at low temperature is a key prerequisite for fully exploiting the potential application value of PtSe2.

[0003] Currently, the main preparation techniques for PtSe2 include low-temperature thermal-assisted conversion (TAC), high-temperature and high-pressure preparation and high-temperature chemical vapor deposition (CVD). In the TAC method, a certain thickness of platinum film or platinum nanobelt is pre-deposited on the surface layer of the growth substrate, and then PtSe2 thin film or nanobelt is obtained by reacting with selenium vapor at about 400℃. Although this method realizes low-temperature synthesis, the product is usually a polycrystalline continuous film, and the crystal domain size is only nanoscale. A large number of grain boundaries cause serious electron scattering, which limits the performance of the material. The high-temperature and high-pressure preparation method is simple and does not require any reaction aids, but the obtained product is a bulk (CN106431407B) rather than a two-dimensional layered PtSe2, which is not conducive to subsequent two-dimensional optoelectronic device applications. The CVD method can prepare larger size PtSe2 single crystals and improve the material performance, but the morphology of the generated PtSe2 single crystals is mainly hexagonal (CN113046827A), and other structural morphologies have not been obtained. At the same time, the high-temperature CVD process needs to be carried out at 800℃ or above, which is difficult to be compatible with the CMOS (complementary metal-oxide-semiconductor) post-process requiring a temperature of ≤450℃, and is not conducive to the application of PtSe2 single crystals in actual devices. SUMMARY

[0004] The present application aims to improve at least one technical problem in the background art.

[0005] The first aspect of the present application provides a platinum diselenide, wherein the morphology of the platinum diselenide is a tetragonal single crystal, a nanostructure with dendritic characteristics, a flake or a continuous film; the tetragonal single crystal is a two-dimensional multilayer quadrilateral; the nanostructure with dendritic characteristics is a two-dimensional multilayer four-petal shape; the flake is a two-dimensional multilayer circle-like shape; and the continuous film is a two-dimensional multilayer continuous film.

[0006] The second aspect of the present application provides a preparation method of the above-mentioned platinum diselenide, comprising the following steps:

[0007] adding a platinum-based precursor into a hydrochloric acid solution to obtain a mixed solution;

[0008] spinning the mixed solution on the surface of a growth substrate, and then performing annealing treatment to obtain a precursor seed crystal, and making selenium vapor diffuse to the precursor seed crystal to react to obtain platinum diselenide by a carrier gas;

[0009] The temperature of the annealing treatment is 120-150°C, and the time of the annealing treatment is 30-60 min;

[0010] The carrier gas is a mixed gas of argon and hydrogen;

[0011] When the morphology of the platinum diselenide is a tetragonal single crystal, the spinning speed is 3000-6000 rpm, the flow rate of the argon is 90 sccm, and the flow rate of the hydrogen is 10 sccm;

[0012] When the morphology of the platinum diselenide is a nanostructure with dendritic characteristics, the spinning speed is 3000-6000 rpm, the flow rate of the argon is 180 sccm, and the flow rate of the hydrogen is 20 sccm;

[0013] When the morphology of the platinum diselenide is a flake, the spinning speed is 1500-2500 rpm, the flow rate of the argon is 90 sccm, and the flow rate of the hydrogen is 10 sccm;

[0014] When the morphology of the platinum diselenide is a continuous film, the spinning speed is not more than 500 rpm, the flow rate of the argon is 90 sccm, and the flow rate of the hydrogen is 10 sccm.

[0015] Further, the annealing is performed in an inert gas atmosphere, and the flow rate of the inert gas is 100-300 sccm.

[0016] Further, the reaction of the selenium vapor with the precursor seed crystal is performed in a first device, the first device comprising a first temperature zone and a second temperature zone, the first temperature zone being in communication with the second temperature zone, the selenium vapor being formed by heating and volatilizing selenium powder, the selenium powder being placed in the first temperature zone, the precursor seed crystal being placed in the second temperature zone, and the carrier gas being introduced into the first temperature zone to make the selenium vapor diffuse to the second temperature zone to react with the precursor seed crystal.

[0017] Further, the temperature of the first temperature zone is 230-300°C, and the temperature of the second temperature zone is 400-550°C.

[0018] Further, the spinning time is 0.5-1.0 min.

[0019] Further, the reaction of the selenium vapor and the precursor crystal seed is carried out under a pressure of 100 Pa to 300 Pa, and the reaction time of the selenium vapor and the precursor crystal seed is 5 min to 30 min. Further, the platinum-based precursor is one of chloroplatinic acid, dichloroplatinum, and tetrachloroplatinic acid.

[0020] Further, the mass fraction of the hydrochloric acid in the hydrochloric acid solution is 37%, and the molar concentration of the platinum element in the mixed solution is 0.01 mol / L to 1.0 mol / L.

[0021] The third aspect of the present application provides an application of the platinum diselenide with a tetragonal single crystal morphology in a field effect transistor.

[0022] The present application has the following beneficial effects: The present application is innovative in morphology and product form, not only prepares platinum diselenide with a tetragonal single crystal morphology, but also creates favorable conditions for fully exerting the potential of different optoelectronic device applications, and can realize controllable preparation of tetragonal single crystals, nanostructures with dendritic characteristics, thin sheets, and continuous thin films through simple parameter adjustment. In terms of process compatibility, the low-temperature preparation process not only effectively avoids the temperature limitations of traditional high-temperature methods, but also breaks through the limitations of crystal domain size in traditional low-temperature methods, and can obtain crystal lateral size that meets the actual application requirements, providing a key guarantee for adaptation to existing processes. In addition, the preparation method of the present application also has excellent technical expandability, and the core process logic and control idea can be extended to low-temperature synthesis of other platinum-based two-dimensional materials, providing a referenceable technical framework for the large-scale and diversified preparation of such materials, further expanding the application range and value of the technology. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 FIG. 1 is a structural schematic diagram of a double-zone tube furnace in an embodiment;

[0024] Figure 2 FIG. 2 is an optical microscope image of a tetragonal platinum diselenide single crystal grown in Example 1;

[0025] Figure 3 FIG. 3 is a Raman spectrum of the tetragonal platinum diselenide single crystal grown in Example 1;

[0026] Figure 4 FIG. 4 is a peak intensity mapping of the tetragonal platinum diselenide single crystal grown in Example 1 at the Raman characteristic peaks E g (178 cm -1 ), and A 1g (206 cm -1 );

[0027] Figure 5 FIG. 5 is an optical microscope image of a platinum diselenide nanostructure grown in Example 2;

[0028] Figure 6 Raman spectrum of the platinum diselenide nanostructure grown in Example 2;

[0029] Figure 7 Mapping of peak intensity at Raman characteristic peaks E g (178 cm -1 ), A 1g (206 cm -1 ) of the platinum diselenide nanostructure grown in Example 2;

[0030] Figure 8 Optical microscope image of the platinum diselenide flake grown in Example 3;

[0031] Figure 9 Raman spectrum of the platinum diselenide flake grown in Example 3;

[0032] Figure 10 Mapping of peak intensity at Raman characteristic peaks E g (178 cm -1 ), A 1g (206 cm -1 ) of the platinum diselenide flake grown in Example 3;

[0033] Figure 11 Optical microscope image of the platinum diselenide continuous film grown in Example 4;

[0034] Figure 12 Raman spectrum of the platinum diselenide continuous film grown in Example 4;

[0035] Figure 13 Output and transfer characteristic curves of the square-shaped platinum diselenide single crystal field effect transistor device grown in Example 1.

[0036] In the drawing: 1 - outer quartz tube; 2 - inner quartz tube; 3 - first temperature zone; 4 - second temperature zone; 5 - growth substrate; 6 - platinum diselenide product; 7 - precursor seed; 8 - selenium powder; 9 - ceramic boat. DETAILED DESCRIPTION

[0037] The application will be further described with reference to the following specific examples. It should be understood that these examples are intended to illustrate the application and are not intended to limit the scope of the application. Furthermore, since modifications and changes can be made within the knowledge of a person skilled in the art, these equivalent forms should also fall within the scope of the claims appended to the present application.

[0038] The embodiment provides a platinum diselenide, wherein the morphology of the platinum diselenide is a tetragonal single crystal, a nanostructure with dendrite characteristics, a flake or a continuous film; the tetragonal single crystal is a two-dimensional multilayer quadrilateral; the nanostructure with dendrite characteristics is a two-dimensional multilayer four-petal shape; the flake is a two-dimensional multilayer circular shape; and the continuous film is a two-dimensional multilayer continuous film.

[0039] The embodiment further provides a preparation method of the platinum diselenide.

[0040] The platinum-based precursor is added into a hydrochloric acid solution to obtain a mixed solution;

[0041] The mixed solution is spin-coated on the surface of a growth substrate, and then annealing treatment is performed to obtain a precursor seed; selenium vapor is diffused to the precursor seed to react with the precursor seed by a carrier gas to obtain the platinum diselenide;

[0042] The temperature of the annealing treatment is 120-150 DEG C, and the time of the annealing treatment is 30-60 min;

[0043] The carrier gas is a mixed gas of argon and hydrogen;

[0044] When the morphology of the platinum diselenide is the tetragonal single crystal, the speed of the spin-coating is 3000-6000 rpm, the flow rate of the argon is 90 sccm, and the flow rate of the hydrogen is 10 sccm;

[0045] When the morphology of the platinum diselenide is the nanostructure with dendrite characteristics, the speed of the spin-coating is 3000-6000 rpm, the flow rate of the argon is 180 sccm, and the flow rate of the hydrogen is 20 sccm;

[0046] When the morphology of the platinum diselenide is the flake, the speed of the spin-coating is 1500-2500 rpm, the flow rate of the argon is 90 sccm, and the flow rate of the hydrogen is 10 sccm;

[0047] When the morphology of the platinum diselenide is the continuous film, the speed of the spin-coating is not more than 500 rpm, the flow rate of the argon is 90 sccm, and the flow rate of the hydrogen is 10 sccm.

[0048] In this method for preparing platinum diselenide, a platinum-based precursor is first added to a hydrochloric acid solution. The key is to use hydrochloric acid to create a uniform dispersion environment and prevent precursor agglomeration. The mixed solution is then spin-coated onto the growth substrate surface. The spin-coating speed directly determines the distribution and final morphology of the platinum-based precursor on the substrate surface. Only at lower spin-coating speeds (not exceeding 500 rpm) will the precursor fully spread and form a continuous platinum-based coating (corresponding to the subsequent continuous film). At other spin-coating speeds, the precursor is distributed discretely and, after annealing, is transformed into independent platinum-based seed crystals. The annealing process uses a low-temperature process of 120℃-150℃ to remove residual solvent to avoid interfering with seed crystal formation and to promote the directional transformation of the discretely distributed precursor into independent platinum-based seed crystals with controllable size and density. In the reaction step with selenium vapor, the initial state of the precursor seed crystals (independent platinum-based seed crystals or continuous platinum-based coating), combined with the control of the carrier gas flow rate, jointly achieves the directional growth of four morphologies. For tetragonal single crystals, dispersed independent seed crystals formed at specific spin coating speeds provide a stable and ordered bonding environment for selenium and platinum atoms under matched carrier gas flow rates, guiding the crystal to grow along a specific direction, avoiding polymorphism or morphological deviation, and ultimately forming independent tetragonal single crystals. When preparing nanostructures with dendritic characteristics, maintaining the same independent seed crystal state as tetragonal single crystals and adjusting only the carrier gas flow rate can change the reaction kinetics, inducing the fractal growth of independent seed crystals, transforming the crystal from a compact tetragonal morphology to a dendritic structure. If the target is a thin sheet, adjusting the spin coating speed changes the density and distribution of independent seed crystals, causing the seed crystals to preferentially grow into tetragonal single crystals in the central region of the substrate, while the independent seed crystals in the peripheral region undergo multiple nucleation and growth, eventually splicing together to form a thin sheet. Continuous thin films are continuous platinum-based coatings formed at extremely low spin coating speeds, which remain continuous after annealing and are transformed into continuous platinum diselenide thin films when reacting with selenium vapor.

[0049] Furthermore, the annealing is carried out in an inert gas atmosphere with a flow rate of 100 sccm-300 sccm.

[0050] The use of an inert gas atmosphere effectively isolates platinum-based precursors from reactive components such as oxygen and water vapor in the air, preventing oxidation or reaction with water vapor to generate impurities during annealing. This ensures that the platinum-based precursors undergo only directional transformation to form pure platinum-containing seed crystals, preventing impurities from interfering with the subsequent growth of platinum diselenide single crystals. On the other hand, the inert gas can act as a carrier gas, more efficiently removing molecules generated by the evaporation of residual solvents during annealing, further improving the purity of the precursor seed crystals. At the same time, it maintains the stability of the annealing environment, preventing problems such as agglomeration and irregular morphology of platinum-containing seed crystals caused by atmospheric fluctuations, and ensuring the uniformity and regularity of the dispersion of platinum-containing seed crystals.

[0051] Furthermore, the reaction between selenium vapor and precursor seed crystals is carried out in a first device, which includes a first temperature zone and a second temperature zone connected to each other. Selenium vapor is formed by the volatilization of selenium powder upon heating. The selenium powder is placed in the first temperature zone, and the precursor seed crystals are placed in the second temperature zone. A carrier gas is introduced into the first temperature zone to allow the selenium vapor to diffuse into the second temperature zone and react with the precursor seed crystals.

[0052] Specifically, the first device is a dual-temperature zone tubular furnace, the structure of which is referenced. Figure 1 As shown, the quartz tube of the dual-temperature zone tube furnace is divided into an outer quartz tube 1 and an inner quartz tube. The dual-temperature zone tube furnace achieves precise reaction through zoned temperature control and directional mass transfer. Taking the preparation of tetragonal single crystal platinum diselenide as an example, selenium powder 8 is placed in the ceramic boat 9 of the first temperature zone 3, and the growth substrate 5 carrying the precursor seed crystal 7 is placed in the second temperature zone 4. This arrangement can regulate the temperature environment of selenium powder 8 volatilization and platinum diselenide single crystal growth separately through the independent temperature control function of the two temperature zones, avoiding the interference of temperature fluctuations in a single temperature zone on the selenium vapor concentration and the growth rate of platinum diselenide single crystal. When the reaction starts, a carrier gas is introduced into the first temperature zone 3. The carrier gas not only maintains the inert atmosphere of the first temperature zone 3 to prevent the oxidation of selenium powder 8, but also acts as a mass transfer carrier, carrying the selenium vapor formed by the volatilization of selenium powder 8 in the first temperature zone 3 to diffuse stably to the second temperature zone 4 along the connecting channel between the two temperature zones. After the selenium vapor entering the second temperature zone 4 comes into contact with the platinum-containing seed crystal (in the precursor seed crystal 7) on the surface of the growth substrate 5, a chemical reaction occurs under low temperature conditions. The platinum-containing seed crystal acts as a reactive center, guiding the selenium atoms and platinum atoms to combine in a specific crystal orientation. Furthermore, thanks to the stable temperature field of the dual temperature zones and the uniform selenium vapor concentration brought by the carrier gas, polycrystalline formation or morphological disorder is effectively avoided. Finally, the product 6 of platinum diselenide with a tetragonal single crystal morphology is formed by directional growth.

[0053] Furthermore, the temperature in the first temperature zone is 230℃-300℃, and the temperature in the second temperature zone is 400℃-550℃.

[0054] Furthermore, the spin coating time is 0.5 min to 1.0 min.

[0055] Furthermore, the reaction between selenium vapor and precursor seed crystals is carried out under a pressure of 100 Pa-300 Pa, and the reaction time is 5 min-30 min. Furthermore, the platinum-based precursor is one of chloroplatinic acid, platinum dichloride, and platinum tetrachloride.

[0056] Preferably, the platinum-based precursor is an aqueous solution of chloroplatinic acid, wherein the mass fraction of chloroplatinic acid in the aqueous solution is 8%.

[0057] Furthermore, the hydrochloric acid in the hydrochloric acid solution has a mass fraction of 37%, and the molar concentration of platinum in the mixed solution is 0.01 mol / L-1.0 mol / L.

[0058] Preferably, the molar concentration of platinum in the mixed solution is 0.1 mol / L.

[0059] Furthermore, the growth substrate is one of SiO2 / Si, sapphire, mica sheet, and quartz sheet.

[0060] Preferably, the growth substrate is SiO2 / Si.

[0061] Furthermore, before spin-coating the mixed solution onto the growth substrate surface, the growth substrate is pretreated by plasma treatment or piranha solution treatment. The plasma is one of oxygen plasma, air plasma, and ozone plasma, and the piranha solution is a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a mass ratio of 7:3.

[0062] Example 1

[0063] A type of platinum diselenide, which has a tetragonal single crystal morphology.

[0064] Its preparation method includes the following steps:

[0065] An aqueous solution of chloroplatinic acid (8% by mass) was added to a hydrochloric acid solution (37% by mass) to obtain a mixed solution (the molar concentration of platinum in the mixed solution was 0.1 mol / L).

[0066] A mixed solution was spin-coated (at a spin speed of 5000 rpm) onto a SiO2 / Si (growth substrate) surface treated with piranha solution (a mixture of concentrated sulfuric acid and hydrogen peroxide in a mass ratio of 7:3). Then, an annealing treatment was performed (the annealing treatment was carried out under an argon atmosphere with a flow rate of 300 sccm, an annealing temperature of 150℃, and an annealing time of 30 min) to obtain precursor seed crystals. Platinum diselenide was obtained by reacting the precursor seed crystals with selenium vapor.

[0067] The reaction between selenium vapor and precursor seed crystals is carried out in the aforementioned dual-temperature zone tube furnace. The selenium vapor is formed by the volatilization of selenium powder upon heating. The selenium powder is placed in the first temperature zone, and the precursor seed crystals are placed in the second temperature zone. A carrier gas (a mixture of argon and hydrogen, with a flow rate of 90 sccm and a flow rate of 10 sccm) is introduced into the first temperature zone to allow the selenium vapor to diffuse into the second temperature zone and react with the precursor seed crystals. The reaction between the selenium vapor and the precursor seed crystals is carried out at a pressure of 120 Pa for 20 minutes.

[0068] An optical microscope image of platinum diselenide prepared in Example 1 is shown below. Figure 2 As shown, it exhibits a unique square morphology. The Raman spectrum of platinum diselenide prepared in Example 1 is as follows. Figure 3 As shown, in its Raman spectrum, ~178 cm⁻¹-1 The Raman peak at that location is the characteristic peak of in-plane vibration of platinum diselenide (i.e., E). g Peak), ~206 cm -1 The Raman peak at this point is the characteristic peak of the out-of-plane vibration of platinum diselenide (i.e., A). 1g Peak); its Raman characteristic peak E g (178 cm) -1 A) 1g (206 cm) -1 The peak intensity mapping at () is shown in the figure. Figure 4 As shown ( Figure 4 In the middle, a is E g Peak intensity mapping at the peak, b represents A 1g The peak intensity mapping at the peak shows uniform color contrast, indicating the structural consistency throughout the crystal.

[0069] Example 2

[0070] A platinum diselenide with a morphology of a dendritic nanostructure.

[0071] The preparation method differs from that in Example 1 in that the flow rate of argon in the carrier gas is 180 ccm and the flow rate of hydrogen is 20 sccm.

[0072] An optical microscope image of platinum diselenide prepared in Example 2 is shown below. Figure 5 As shown, it exhibits typical kinetically controlled fractal growth characteristics, with the crystal shape changing from a tetragonal single crystal in Example 1 to a dendritic nanostructure, while still retaining its tetragonal structural features. The Raman spectrum of platinum diselenide prepared in Example 2 is shown below. Figure 6 As shown, the Raman spectra at three random positions are consistent, indicating structural consistency; its Raman characteristic peak E g (178 cm) -1 A) 1g (206 cm) -1 The peak intensity mapping at () is shown in the figure. Figure 7 As shown ( Figure 7 In the middle, a is E g Peak intensity mapping at the peak, b represents A 1g The peak intensity mapping at the peak shows uniform color contrast, indicating the structural consistency of the entire platinum diselenide nanostructure.

[0073] Example 3

[0074] A type of platinum diselenide, which has the morphology of a thin sheet.

[0075] The preparation method differs from that in Example 1 in that the spin coating speed is 1500 rpm.

[0076] An optical microscope image of platinum diselenide prepared in Example 3 is shown below. Figure 8 As shown, the growth process is as follows: at a relatively slow spin-coating speed, the platinum-containing seed crystals obtained on the substrate surface are relatively large. A square-shaped platinum diselenide single crystal preferentially forms at the seed crystal center. Multiple nucleation processes occur around the single crystal, generating platinum diselenide flakes with a maximum lateral size of up to 20 μm. The Raman spectrum of the platinum diselenide prepared in Example 3 is shown below. Figure 9 As shown, in its Raman spectrum, the two Raman characteristic peaks of the inner single crystal exhibit a certain red shift compared to the outer thin film, indicating that the thickness of the inner single crystal is greater than that of the outer thin film; its Raman characteristic peak E g (178 cm) -1 A) 1g (206 cm) -1 The peak intensity mapping at () is shown in the figure. Figure 10 As shown ( Figure 10 In the middle, a is E g Peak intensity mapping at the peak, b represents A 1g The peak intensity mapping at the peak shows uniform color contrast, indicating the structural consistency of the entire platinum diselenide sheet.

[0077] Example 4

[0078] A platinum diselenide, which has the morphology of a continuous thin film.

[0079] The preparation method differs from that in Example 1 in that the spin coating speed is 500 rpm.

[0080] An optical microscope image of platinum diselenide prepared in Example 4 is shown below. Figure 11 As shown, the growth process is as follows: at extremely slow spin-coating speeds, the precursor solution covers the entire surface of the growth substrate, making it difficult to effectively form independently distributed seed crystals, and resulting in the formation of continuous thin films after growth. The Raman spectrum of platinum diselenide prepared in Example 4 is shown below. Figure 12 As shown, the Raman spectra at two random positions are consistent, indicating that its structure is consistent.

[0081] Field-effect transistor device applications

[0082] Using the tetragonal single-crystal platinum diselenide obtained in Example 1, a field-effect transistor (FET) device based on multilayer platinum diselenide (tetragonal single crystal) was fabricated. Its output and transfer characteristic curves are shown below. Figure 13 As shown ( Figure 13 In the curve (a is the output curve, b is the transfer curve), on the output curve, the drain current I... ds With the source-drain voltage V dsThe linear increase in voltage V suggests an ohmic contact; on the transfer curve, as the gate voltage V increases... gs Change, drain current I ds These results can be modulated by minute gate voltage amplitudes, consistent with the characteristics of multilayer platinum diselenide as a two-dimensional semi-metal, revealing its application prospects as a two-dimensional van der Waals metal with low contact resistance. When traditional three-dimensional metals (such as gold and titanium) contact two-dimensional semiconductors (such as MoS2), high contact resistance arises due to severe Fermi level pinning and interface defects, becoming a bottleneck limiting the performance of two-dimensional devices. The advantage of platinum diselenide lies in solving these problems, based on its inherent van der Waals interface, where it is bonded to another two-dimensional material via van der Waals forces when stacked as an electrode. This interface is free of dangling bonds and atomically flat, minimizing interface scattering and defect states, thus significantly reducing contact resistance.

[0083] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing platinum diselenide, characterized in that, The platinum diselenide has the morphology of a tetragonal single crystal or a nanostructure with dendritic features; the tetragonal single crystal is a two-dimensional multilayered quadrilateral; the nanostructure with dendritic features is a two-dimensional multilayered four-petal-shaped structure. The preparation method of platinum diselenide includes the following steps: The platinum-based precursor was added to a hydrochloric acid solution to obtain a mixed solution; The mixed solution is spin-coated onto the surface of the growth substrate and then annealed to obtain a precursor seed crystal. Selenium vapor is diffused through a carrier gas to react with the precursor seed crystal to obtain platinum diselenide. The annealing temperature is 120℃-150℃, and the annealing time is 30min-60min; The carrier gas is a mixture of argon and hydrogen. When the morphology of the platinum diselenide is the tetragonal single crystal, the spin coating speed is 3000rpm-6000rpm, the argon flow rate is 90sccm, and the hydrogen flow rate is 10sccm. When the morphology of the platinum diselenide is the nanostructure with dendritic characteristics, the spin coating speed is 3000rpm-6000rpm, the argon flow rate is 180sccm, and the hydrogen flow rate is 20sccm. The reaction between the selenium vapor and the precursor seed crystal is carried out in a first device, which includes a first temperature zone and a second temperature zone. The first temperature zone and the second temperature zone are connected. The selenium vapor is formed by the volatilization of selenium powder upon heating. The selenium powder is placed in the first temperature zone, and the precursor seed crystal is placed in the second temperature zone. The carrier gas is introduced into the first temperature zone to allow the selenium vapor to diffuse into the second temperature zone and react with the precursor seed crystal.

2. The method for preparing platinum diselenide according to claim 1, characterized in that, The annealing is carried out in an inert gas atmosphere with a flow rate of 100 sccm-300 sccm.

3. The method for preparing platinum diselenide according to claim 1, characterized in that, The temperature of the first temperature zone is 230℃-300℃, and the temperature of the second temperature zone is 400℃-550℃.

4. The method for preparing platinum diselenide according to claim 1, characterized in that, The spin coating time is 0.5 min to 1.0 min.

5. The method for preparing platinum diselenide according to claim 1, characterized in that, The reaction between the selenium vapor and the precursor seed crystal is carried out under a pressure of 100 Pa to 300 Pa, and the reaction time between the selenium vapor and the precursor seed crystal is 5 min to 30 min.

6. The method for preparing platinum diselenide according to claim 1, characterized in that, The platinum-based precursor is one of chloroplatinic acid, platinum dichloride, and platinum tetrachloride.

7. The method for preparing platinum diselenide according to claim 1, characterized in that, The hydrochloric acid solution contains 37% hydrochloric acid by mass, and the molar concentration of platinum in the mixed solution is 0.01 mol / L to 1.0 mol / L.

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