A perovskite single crystal nanosheet and its preparation method and application

Abstract

The present invention discloses a perovskite single crystal nanosheet, its preparation method, and application. The method comprises the following steps: 1) mixing a raw material for a B-site cation, a raw material for an A-site cation, and an organic solvent to obtain a perovskite precursor solution; 2) contacting and reacting the perovskite precursor solution with an antisolvent to obtain a complex of perovskite and the organic solvent; 3) placing the complex of perovskite and the organic solvent on a first substrate, applying pressure to the complex of perovskite and the organic solvent to decompose it, obtaining a saturated perovskite solution, and removing the organic solvent to obtain the perovskite single crystal nanosheet. The method of the present invention utilizes an antisolvent diffusion method to prepare the complex of perovskite and the organic solvent under normal pressure and low temperature, which facilitates the subsequent rapid and high-quality growth of the perovskite single crystal nanosheet. The prepared perovskite single crystal nanosheet can achieve high device responsiveness, high response speed, and high stability in the short-wave infrared band.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells and relates to a perovskite single crystal nanosheet and a preparation method and application thereof. Background Art

[0002] Photodetectors are the foundation of modern industrial interconnection and artificial intelligence. They convert optical signals into editable electrical signals, making them a critical component for connecting disparate devices. A key performance indicator for photodetectors is their wide spectral response, indicating their ability to capture optical signals across a wide spectral range, including ultraviolet (UV), visible (Vis), near-infrared (NIR), and short-wave infrared (SWIR). In particular, photodetectors with high performance in the NIR and SWIR bands have found deeper and broader applications in specialized fields such as biomedical health, national defense and security, autonomous driving, machine vision, imaging, and optical communications.

[0003] The photoactive materials of commercial infrared detectors are typically inorganic non-metallic materials, such as silicon (Si), germanium (Ge), and indium gallium arsenide (InGaAs). These materials present the following challenges: ① The growth of these crystals requires an extremely stringent high-temperature, high-vacuum environment, resulting in high energy consumption; ② Photodetectors based on these materials place high demands on crystal quality and purity; and ③ Inorganic non-metallic materials lack the flexibility required of new optoelectronic devices.

[0004] The metal halide perovskite (ABX3) prepared by low-temperature solution method has a high absorption coefficient (~105cm -1 ), high photoresponse can be achieved with less photoactive material; its band gap is adjustable (1.17-2.88eV), and it has excellent optoelectronic properties such as wide spectral response and high defect tolerance (no need for high crystal quality and high purity), high carrier mobility (fast device response speed), long carrier lifetime and diffusion length (high device gain). Moreover, the low-temperature solution method has the advantages of low energy consumption and low cost, which has enabled it to be widely and comprehensively developed in photodetectors.

[0005] Metal halide perovskites are generally divided into tin-based metal halide perovskites and lead-based metal halide perovskites. 2+ ) is easily oxidized to tetravalent tin (Sn 4+), resulting in p-type self-doping, which transforms tin-based metal halide perovskites from semiconductors to metalloids, shortening carrier diffusion lengths and degrading photoelectric properties. This results in poor device performance and stability in near-infrared detectors based on tin-based metal halide perovskites. Lead-based metal halide perovskites offer better long-term stability and repeatability, but their band gaps are typically greater than 1.5 eV, making them virtually non-photoresponsive in the infrared spectral range.

[0006] To achieve infrared light detection in lead-based metal halide perovskites, a common approach is to combine them with narrow-bandgap semiconductors or upconversion nanoparticles to achieve spectral complementary absorption. This presents the following challenges: ① The poor energy level matching between the metal halide perovskite and narrow-bandgap semiconductor materials leads to weak near-infrared light absorption and / or low efficiency in extracting photogenerated carriers, resulting in a low near-infrared light response in the device; ② The incorporated narrow-bandgap semiconductor material affects the crystallization quality of the metal halide perovskite crystal, introducing non-radiative recombination defects, thereby reducing the device's photocurrent and increasing its dark current; and ③ The addition of narrow-bandgap semiconductor materials during device fabrication increases material costs and device fabrication complexity. Furthermore, thermal radiation and plasmon effects can also be used to achieve near-infrared light response in lead-based metal halide perovskite detectors. However, carrier aggregation and thermal effects can lead to rapid device aging and a sharp decline in performance.

[0007] Lead-based metal halide perovskites, the photoactive materials in lead-based metal halide perovskites, exist in the following main morphologies: polycrystalline thin films, bulk single crystals, and nano / micron single crystals. Compared to polycrystalline thin films, single crystals have fewer grain boundaries and non-radiative recombination centers, which improves carrier transport efficiency and device photoelectric conversion efficiency. However, due to their large size, bulk single crystals of metal halide perovskites cannot be integrated with active electronic and optical devices on planar substrates. Generally, photodetectors based on nano / micron single crystal metal halide perovskites are easy to integrate with other electronic components. However, most reported photodetectors based on nano / micron single crystal metal halide perovskites have a large amount of nano / micron single crystal metal halide perovskites in their channel, and the presence of numerous grain boundaries between the nano / micron single crystal metal halide perovskites reduces the device's photoelectric performance.

[0008] At the same time, there is trap-related sub-gap absorption in bulk metal halide perovskite single crystals, which can realize near-infrared light response of lead-based metal halide perovskite photodetectors at lower incident light intensity.

[0009] However, the spectral response region of photodetectors based on sub-bandgap absorption of surface defect states of lead-based metal halide perovskites in existing literature is limited to the near-infrared region (~900nm), and there are still no reports of photodetectors based on lead-based metal halide perovskites with high responsivity, high response speed and high stability in the short-wave infrared band. Summary of the Invention

[0010] In view of the above problems existing in the prior art, the object of the present invention is to provide a perovskite single crystal nanosheet and a preparation method and application thereof.

[0011] To achieve the above object, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a method for preparing a perovskite single crystal nanosheet, the method comprising the following steps:

[0013] (1) mixing a raw material of a B-site cation, a raw material of an A-site cation, and an organic solvent to obtain a perovskite precursor solution;

[0014] (2) contacting and reacting the perovskite precursor solution described in step (1) with an antisolvent to obtain a complex of perovskite and an organic solvent;

[0015] (3) placing the complex of the perovskite and the organic solvent on a first substrate, applying pressure to the complex of the perovskite and the organic solvent to decompose it, obtaining a saturated perovskite solution, and removing the organic solvent to obtain the perovskite single crystal nanosheet.

[0016] The method of the present invention utilizes antisolvent diffusion to prepare a complex of perovskite and an organic solvent under normal pressure and low temperature. This facilitates the subsequent rapid and high-quality growth of perovskite single-crystal nanosheets, resulting in sharp corners and a smooth surface. This method reduces the manufacturing cost of photodetectors, and the perovskite single-crystal nanosheet material is flexible, making it suitable for flexible devices.

[0017] The perovskite single crystal nanosheet prepared by the method of the present invention has a longitudinal thickness of nanometer level and a lateral size of micrometer level, a large specific surface area, and many surface defect states, and can achieve high responsiveness, high response speed and high stability of the device in the short-wave infrared band.

[0018] In the present invention, the term "nanoscale" in longitudinal thickness refers to a thickness of less than 1000 nm, such as 1000 nm, 900 nm, 800 nm, 750 nm, 700 nm, 650 nm, 600 nm, 550 nm, 500 nm, 450 nm, 400 nm, 350 nm, 300 nm, 200 nm, 100 nm, or 50 nm. The term "micrometer-scale" in lateral dimension refers to a line width on a two-dimensional plane of less than 100 μm, such as 1 μm, 3 μm, 4 μm, 5 μm, 7 μm, 10 μm, 12 μm, 13 μm, 15 μm, 17 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or 60 μm. Line width refers to the distance between two points on the edge of a two-dimensional plane and a line connecting the two points through the center of the two-dimensional plane.

[0019] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0020] Preferably, the raw material in which B is a cation in step (1) is at least one of lead halide, tin halide and bismuth halide.

[0021] Preferably, the lead halide includes at least one of PbCl2, PbBr2, PbI2, SnCl2, SnBr2, SnI2, BiCl2, BiBr2 and BiI2.

[0022] Preferably, the raw material of the A-site cation in step (1) is at least one of an organic halide and an inorganic halide, preferably including at least one of MACl, MABr, MAI, FACl, FABr, FAI, CsCl, CsBr, CsI, RbCl, RbBr and RbI, wherein MA + It can be CH3NH3 + , FA + It can be HN=CHNH3 + .

[0023] The present invention does not specifically limit the type of the organic solvent in step (1), including but not limited to at least one of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0024] Preferably, the mixing in step (1) is carried out at room temperature and is accompanied by stirring.

[0025] In one embodiment, in step (1), the mixture is stirred at room temperature to fully dissolve the raw materials of the B-site cations and the raw materials of the A-site cations to obtain a clear and transparent perovskite precursor solution.

[0026] In the present invention, normal temperature refers to 25 to 40°C, for example, 25°C, 27°C, 30°C, 33°C, 36°C, 38°C or 40°C.

[0027] Preferably, the concentration of the perovskite precursor solution in step (1) is 0.5 to 5 mol / L, for example, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L or 5 mol / L.

[0028] Preferably, the perovskite precursor solution in step (1) is filtered, and the pore size of the filter element is 0.2 to 0.5 μm, such as 0.2 μm, 0.3 μm, 0.4 μm or 0.5 μm. This step can filter out undissolved residues, which is beneficial to improving the purity of the precursor solution.

[0029] The present invention does not limit the specific type of the filter component, for example, it can be filter paper or a filter head.

[0030] As a preferred technical solution of the method of the present invention, the method of contacting and reacting the perovskite precursor solution of step (1) with an anti-solvent in step (2) comprises:

[0031] (a) placing the perovskite precursor solution described in step (1) in an open first container;

[0032] (b) placing the first container into a second container containing an antisolvent and sealing the container;

[0033] (c) placing the second container in a low temperature environment for a period of time to obtain a complex of the perovskite and the organic solvent.

[0034] In some optional embodiments, the volume of the first container is V1, the volume of the second container is V2, V1 / V2=(1-50) / (100-500), wherein the selection range of V1 "1-50" can be, for example, 1, 3, 5, 8, 10, 15, 20, 25, 30, 35, 40, 45 or 50, etc.; the selection range of V2 "100-500" can be, for example, 100, 110, 120, 130, 140, 150, 160, 170, 200, 220, 240, 260, 280, 300, 350, 400, 450 or 500, etc.

[0035] Preferably, the volume of the anti-solvent is V3, V3 / V2=(100-300) / (100-500), wherein the selection range of V3 "100-300" can be, for example, 100, 120, 150, 180, 200, 220, 240, 260, 280 or 300, etc.; the selection range of V2 "100-500" can be, for example, 100, 110, 120, 130, 140, 150, 160, 170, 200, 220, 240, 260, 280, 300, 350, 400, 450 or 500, etc.

[0036] Preferably, the anti-solvent comprises at least one of diethyl ether, chlorobenzene, toluene, anisole and dichloromethane.

[0037] Preferably, the temperature of the low-temperature environment is -10 to 10°C, such as -10°C, -5°C, -3°C, 0°C, 2°C, 4°C, 5°C, 8°C or 10°C.

[0038] Preferably, the period of time is 12 to 72 hours, for example, 12 hours, 15 hours, 17 hours, 18 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, 65 hours or 70 hours, etc.

[0039] As another preferred technical solution of the method of the present invention, the method of applying pressure to the complex of the perovskite and the organic solvent in step (3) includes:

[0040] A second substrate is placed on the side of the first substrate having the complex of perovskite and organic solvent, and pressure is applied between the first substrate and the second substrate to pressurize the complex of perovskite and organic solvent.

[0041] The present invention does not specifically limit the materials of the first substrate and the second substrate. Those skilled in the art can select any substrate as needed. By way of example and not limitation, the first substrate and the second substrate are independently selected from any one of a PDMS soft film, a glass sheet, a silicon wafer, a mica sheet or a sapphire.

[0042] Preferably, the first substrate and / or the second substrate is hydrophilically treated before use.

[0043] Preferably, the hydrophilic treatment is performed by vacuum plasma treatment.

[0044] The substrate is hydrophilized by vacuum plasma treatment, making the substrate surface hydrophilic, which is conducive to the formation of a thinner perovskite saturated solution on its surface, and further conducive to the growth of thinner perovskite single crystal nanosheets, making it larger in specific surface area, and thus conducive to improving the light response of the short-wave infrared light detector prepared using it.

[0045] Preferably, during the vacuum plasma treatment, the power is 50 to 500 W, for example, 50 W, 60 W, 70 W, 80 W, 100 W, 125 W, 150 W, 180 W, 200 W, 230 W, 260 W, 300 W, 350 W, 400 W, 450 W or 500 W, etc.; the time is 1 to 10 minutes, for example, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes or 10 minutes, etc.

[0046] Preferably, the amount of the complex of perovskite and organic solvent used satisfies the following conditions: the ratio of the mass of the complex of perovskite and organic solvent to the area of the first substrate is (0.1-1) mg / 1 cm 2 , for example 0.1mg / 1cm 2 , 0.2mg / 1cm 2 , 0.3mg / 1cm 2 , 0.5mg / 1cm 2 , 0.6mg / 1cm 2 , 0.8mg / 1cm 2 or 1 mg / 1 cm 2 wait.

[0047] Preferably, the applied pressure is 0.1-1 N, such as 0.1 N, 0.2 N, 0.3 N, 0.4 N, 0.5 N, 0.6 N, 0.8 N or 1 N. By adjusting the pressure, the distance between the first substrate and the second substrate can be adjusted.

[0048] Preferably, the pressure is applied and the mixture is left standing for 3 to 10 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes.

[0049] Preferably, the temperature for removing the organic solvent is 20-40°C, for example, 20°C, 23°C, 25°C, 27°C, 28°C, 30°C, 34°C, 37°C or 40°C.

[0050] Preferably, the pressure for removing the organic solvent is one atmosphere.

[0051] In a second aspect, the present invention provides a perovskite single crystal nanosheet prepared by the method described in the first aspect.

[0052] The present invention does not limit the specific composition of the perovskite single crystal nanosheet, and it can be, for example, a lead-based metal halide perovskite single crystal nanosheet.

[0053] Preferably, the thickness of the perovskite single crystal nanosheet is 50 to 1000 nm, for example, 50 nm, 65 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm or 1000 nm.

[0054] Preferably, the lateral size of the perovskite single crystal nanosheet is 1 to 50 μm, for example, 1 μm, 3 μm, 4 μm, 5 μm, 7 μm, 10 μm, 12 μm, 13 μm, 15 μm, 17 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, etc.

[0055] The perovskite single crystal nanosheet prepared by the present invention has a longitudinal thickness of nanometer level and a lateral area of micrometer level, a large specific surface area, and many surface defect states, and can achieve high responsiveness, high response speed and high stability of the device in the short-wave infrared band.

[0056] In a third aspect, the present invention provides a short-wave infrared light detector, which includes an electrode and a perovskite single crystal nanosheet located on the surface of the electrode, wherein the electrode includes a first electrode and a second electrode arranged side by side and spaced apart, a channel is formed between the first electrode and the second electrode, and only a single perovskite single crystal nanosheet exists in the channel.

[0057] In the present invention, “there is only a single perovskite single crystal nanosheet in the channel” means that the channel is only partially covered by one perovskite single crystal nanosheet.

[0058] The short-wave infrared light detector provided by the present invention is based on a single perovskite single crystal nanosheet. There is only a single perovskite single crystal nanosheet in its channel. The device structure is simple, there are no redundant grain boundaries in the channel, there are few non-radiative recombination centers, and it is easy to integrate with active electronic and optical devices.

[0059] The perovskite single crystal nanosheet in the short-wave infrared light detector of the present invention can be the perovskite single crystal nanosheet described in the second aspect, which has a large specific surface area and many surface defect states. The short-wave infrared light detector is a short-wave infrared light detector based on sub-bandgap absorption of surface defects, which has the advantages of high responsiveness, high response speed and high stability.

[0060] The present invention does not limit the specific types of the first electrode and the second electrode, which can be metal electrodes or other conductive electrodes. The materials of the electrodes can be, for example, gold, silver, graphene, etc.

[0061] In a fourth aspect, the present invention provides a method for preparing the short-wave infrared light detector according to the third aspect, the method comprising the following steps:

[0062] Taking a substrate having a perovskite single crystal nanosheet on its surface, using a transfer platform, pressing a transfer film onto a selected single perovskite single crystal nanosheet, so that the transfer film and the single perovskite single crystal nanosheet are in contact, and then lifting the transfer film to obtain a transfer film with the perovskite single crystal nanosheet attached to its surface;

[0063] The transfer film is pressed onto a substrate having electrodes on its surface, wherein the electrodes include a first electrode and a second electrode arranged opposite to each other, and only a single perovskite single crystal nanosheet exists between the first electrode and the second electrode, thereby obtaining the short-wave infrared light detector.

[0064] Preferably, the distance between the first electrode and the second electrode is 1-100 μm, for example, 1 μm, 3 μm, 5 μm, 7 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm or 100 μm, etc. The distance here is the width of the channel.

[0065] The numerical range described in the present invention includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] (1) The method of the present invention utilizes an antisolvent diffusion method to prepare a complex of perovskite and an organic solvent under normal pressure and low temperature, which facilitates the rapid and high-quality growth of subsequent perovskite single crystal nanosheets. The method of the present invention reduces the manufacturing cost of photodetectors, and the perovskite single crystal nanosheet material has the characteristics of flexibility and can be adapted to flexible devices.

[0068] (2) The perovskite single crystal nanosheets prepared by the method of the present invention have a longitudinal thickness of nanometers and a lateral area of micrometers, a large specific surface area, and many surface defect states, which can achieve high responsiveness, high response speed and high stability of the device in the short-wave infrared band.

[0069] (3) The substrate is treated with vacuum plasma to be hydrophilic, making the substrate surface hydrophilic, which is conducive to the formation of a thinner perovskite saturated solution on its surface, and further conducive to the growth of thinner perovskite single crystal nanosheets, making it larger in specific surface area, and thus conducive to improving the light response of the short-wave infrared light detector prepared using it.

[0070] (4) The short-wave infrared light detector provided by the present invention is based on a single perovskite single crystal nanosheet. There is only a single perovskite single crystal nanosheet in its channel. The device structure is simple, there are no redundant grain boundaries in the channel, there are few non-radiative recombination centers, and it is easy to integrate with active electronic and optical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is an optical photograph of the complex of the lead-based metal halide perovskite and the organic solvent in Example 1 of the present invention.

[0072] Figure 2 This is a diagram of the growth process of the lead-based metal halide perovskite single crystal nanosheet MAPbBr3 in Example 1.

[0073] Figure 3 This is a scanning electron microscope image of the lead-based metal halide perovskite single crystal nanosheet in Example 1 of the present invention.

[0074] Figure 4 1 is an atomic force microscope image of the lead-based metal halide perovskite single crystal nanosheet in Example 1 of the present invention and its dimensional parameters.

[0075] Figure 5 It is a schematic diagram of the structure of a PDMS soft film with lead-based metal halide perovskite single crystal nanosheets attached, a schematic diagram of the structure of a substrate with two metal electrodes on the surface, and a schematic diagram of the structure of a short-wave infrared light detector based on a single lead-based metal halide perovskite single crystal nanosheet.

[0076] Figure 6 These are SEM images of the lead-based metal halide perovskites of Examples 2-4. The scale bar in the figure is 10 μm. (a) corresponds to Example 2, (b) corresponds to Example 3, and (c) corresponds to Example 4.

[0077] Figure 7 These are SEM images of the lead-based metal halide perovskites of Examples 1 and 5, where the scale bar is 10 μm, (a) and (c) correspond to Example 5, and (b) and (d) correspond to Example 1.

[0078] Figure 8 This is an optical microscope image of the short-wave infrared light detector based on a single lead-based metal halide perovskite single crystal nanosheet in Application Example 1.

[0079] Figure 9 Schematic diagram of the structure of a short-wave infrared light detector based on a single lead-based metal halide perovskite single crystal nanosheet in one embodiment of the present invention.

[0080] Figure 10 This is a graph showing the wavelength-dependent responsivity of a short-wave infrared photodetector based on a single lead-based metal halide perovskite single crystal nanosheet.

[0081] Figure 11 This is the growth process of the lead-based metal halide perovskite single crystal nanosheet in Example 6 of the present invention.

[0082] Figure 12 This is an optical microscope image of the lead-based metal halide perovskite single crystal nanosheet of Example 7 of the present invention.

[0083] Figure 13 Schematic diagram of an imaging device based on a short-wave infrared light detector in one embodiment of the present invention.

[0084] Figure 14 It is an imaging pattern based on a short-wave infrared light detector in one embodiment of the present invention. DETAILED DESCRIPTION

[0085] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0086] Example 1

[0087] This embodiment provides a method for preparing a lead-based metal halide perovskite single crystal nanosheet, comprising the following steps:

[0088] (1) PbBr2 and MABr (wherein, MA + CH3NH3 + ) was dissolved in NMF and stirred at room temperature until fully dissolved to obtain a lead-based metal halide perovskite precursor solution with a concentration of 1 mol / L, which was filtered and placed in a small glass bottle (volume 50 mL);

[0089] The pore size of the filter head used for filtration is 0.3 μm;

[0090] (2) A small glass bottle (open, not sealed) containing a lead-based metal halide perovskite precursor solution was placed in a sealed large glass bottle (volume 400 mL, anti-solvent volume 200 mL) containing an anti-solvent (chlorobenzene). The large glass bottle was placed in a low-temperature environment of -5°C. After 48 hours, a complex of lead-based metal halide perovskite and an organic solvent was obtained, whose chemical formula is MAPbBr3·DMF.

[0091] Figure 1 : is an optical photograph of the complex of the lead-based metal halide perovskite and the organic solvent in this embodiment. As can be seen from the figure, the complex is white needle-shaped crystals.

[0092] (3) Treat the substrate (silicon wafer) with a vacuum plasma treatment apparatus at a power of 50W for 1 minute to make its surface hydrophilic. Take 5mg of the complex of lead-based metal halide perovskite and organic solvent and place it on the treated substrate (area 10cm 2) (Calculation shows that the mass ratio of the complex of lead-based metal halide perovskite and organic solvent to the area of the treated substrate is 0.5 mg / cm 2 ) and placed on top of it another substrate (silicon wafer) of the same area that had been plasma-treated using the same process. By applying pressure (0.5N) between the two substrates, the spacing between them was controlled. The complex of the lead-based metal halide perovskite and the organic solvent gradually decomposed, forming a saturated solution of the lead-based metal halide perovskite. After 5 minutes (this process was observed in real time and photographed), at a temperature of 25°C and a pressure of 1 atmosphere, as the organic solvent evaporated, a lead-based metal halide perovskite single crystal nanosheet was formed between the two substrates.

[0093] Figure 2 This is a diagram of the growth process of lead-based metal halide perovskite single crystal nanosheets. As can be seen from the picture, white needle-shaped crystals (MAPbBr3·DMF) gradually grow into lead-based metal halide perovskite single crystal nanosheets (MAPbBr3).

[0094] Figure 3 This is a scanning electron microscope image of the lead-based metal halide perovskite single crystal nanosheet in this example. As can be seen from the image, the lead-based metal halide perovskite single crystal nanosheet has sharp edges and a smooth surface, demonstrating its high crystal quality. The lateral dimensions of the lead-based metal halide perovskite single crystal nanosheet are approximately 5 to 10 μm.

[0095] Figure 4 This is an atomic force microscope image of the lead-based metal halide perovskite single crystal nanosheet in this embodiment and its dimensional parameters. It can be seen from the height profile that the surface of the lead-based metal halide perovskite single crystal nanosheet is flat, with a height of about 250nm, a length of about 11.8μm, and a width of about 11.5μm.

[0096] Application Example 1

[0097] This application example provides a short-wave infrared light detector based on a single lead-based metal halide perovskite single crystal nanosheet. The preparation method thereof adopts the lead-based metal halide perovskite single crystal nanosheet prepared in Example 1, and specifically comprises the following steps:

[0098] ① Through the two-dimensional material transfer platform, the PDMS soft film is slowly pressed onto the selected single lead-based metal halide perovskite single crystal nanosheet. After the two are fully in contact, the PDMS soft film is slowly lifted. At this time, the selected single lead-based metal halide perovskite single crystal nanosheet leaves the original substrate and adheres to the PDMS soft film, as shown in the following figure. Figure 5 As shown in the upper left figure, 101 is a lead-based metal halide perovskite single crystal nanosheet, and 106 is a PDMS soft film.

[0099] ② The PDMS soft film with a single lead-based metal halide perovskite single crystal nanosheet attached is slowly pressed onto a substrate with two metal electrodes on its surface. The metal electrodes are made of gold and are arranged side by side with a distance of 8μm between them. There is an insulating layer between them. The substrate is composed of a Si wafer and a 200nm SiO2 layer located on the Si wafer. Only a single lead-based metal halide perovskite single crystal nanosheet exists between the two metal electrodes. At this time, a short-wave infrared light detector based on a single lead-based metal halide perovskite single crystal nanosheet is obtained. The structural diagram of the substrate with two metal electrodes is shown in Figure 2. Figure 5 The lower left figure shows the schematic diagram of the short-wave infrared photodetector based on a single lead-based metal halide perovskite single crystal nanosheet. Figure 5 In the lower right figure, 105 is a Si wafer, 104 is a SiO2 layer, 103 is an insulating layer, and 102 is a metal electrode.

[0100] Figure 8 This is an optical microscope image of the short-wave infrared light detector based on a single lead-based metal halide perovskite single crystal nanosheet in this application example. As can be seen from the image, the length and width of the lead-based metal halide perovskite single crystal nanosheet are about 12μm, the channel is about 8μm, and the lead-based metal halide perovskite single crystal nanosheet is in close contact with the gold electrode.

[0101] Figure 9 This is a schematic structural diagram of a short-wave infrared light detector based on a single lead-based metal halide perovskite single crystal nanosheet in this application example, wherein 101 is a lead-based metal halide perovskite single crystal nanosheet, 102 is a metal electrode, 103 is an insulating layer (i.e., a device channel), 104 is SiO2, and 105 is a Si sheet.

[0102] Wide spectrum imaging test:

[0103] The imaging principle, device, and imaging results are as follows:

[0104] An image mask is inserted between the light source (laser, LED, ultraviolet, visible, near-infrared and short-wave infrared light) and the short-wave infrared photodetector based on a single lead-based metal halide perovskite single crystal nanosheet. The image mask can be moved along the XY direction. Figure 13This is a schematic diagram of an imaging device based on a short-wave infrared photodetector. The light source, lens, chopper, and detector are on the same horizontal line. Line a is connected to a computer, line b is connected to a stepper motor controller, and line c is connected to a semiconductor analyzer. The light source remains constantly on. When the image mask moves in the XY plane, the light irradiating the short-wave infrared photodetector based on a single lead-based metal halide perovskite single crystal nanosheet can be switched on and off according to the hollow pattern on the image mask. Imaging of the hollow pattern on the image mask can be achieved by recording the spatially resolved photocurrent of the short-wave infrared photodetector based on a single lead-based metal halide perovskite single crystal nanosheet at each pixel in real time. For imaging patterns based on short-wave infrared photodetectors, see [ 1 ]. Figure 14 .

[0105] Figure 8 This is a graph showing the change in the responsivity of a short-wave infrared light detector based on a single lead-based metal halide perovskite single crystal nanosheet with wavelength. As can be seen from the figure, the short-wave infrared light detector based on a single lead-based metal halide perovskite single crystal nanosheet responds to light of 850, 950, 1350 and 1450nm, with a photocurrent between 50 and 70pA and a responsivity between 0.04 and 0.08mA / W.

[0106] Example 2

[0107] The difference from Example 1 is that the ratio of the mass of the complex of lead-based metal halide perovskite and organic solvent to the area of the treated substrate is 0.05 mg / cm 2 .

[0108] Example 3

[0109] The difference from Example 1 is that the ratio of the mass of the complex of lead-based metal halide perovskite and organic solvent to the area of the treated substrate is 0.3 mg / cm 2 .

[0110] Example 4

[0111] The difference from Example 1 is that the ratio of the mass of the complex of lead-based metal halide perovskite and organic solvent to the area of the treated substrate is 1.5 mg / cm 2 .

[0112] The effect of the amount of the complex of lead-based metal halide perovskite and organic solvent on the generated lead-based metal halide perovskite was investigated through Examples 2-4. The SEM images of the lead-based metal halide perovskite of Examples 2-4 are shown in FIG. Figure 6As can be seen from the figure, in Example 2, the amount of the complex of the lead-based metal halide perovskite and the organic solvent is too small, resulting in the generated MAPbBr3 perovskite single crystal nanosheets being too small, about 100 nm; when the amount of the complex of the lead-based metal halide perovskite and the organic solvent is appropriate (the ratio of the mass of the complex of the lead-based metal halide perovskite and the organic solvent to the area of the treated substrate is 0.1-1 mg / cm 2 ), the generated MAPbBr3 perovskite single crystal nanosheets are of moderate size, about 10 μm; in Example 4, the amount of the complex of the lead-based metal halide perovskite and the organic solvent is too much, resulting in the stacking and merging of the generated MAPbBr3 perovskite single crystal nanosheets.

[0113] Example 5

[0114] The difference from Example 1 is that the silicon wafers used in step (3) are not plasma treated.

[0115] The effect of substrate hydrophilic treatment on the generated lead-based metal halide perovskite was investigated through Examples 1 and 5. The SEM images of the lead-based metal halide perovskite of Examples 1 and 5 are shown in FIG. Figure 7 As can be seen from the figure, the substrate in Example 5 was not hydrophilized, resulting in stacking of the generated MAPbBr3 perovskite single crystal nanosheets; the substrate in Example 1 was hydrophilized, and the generated MAPbBr3 perovskite single crystal nanosheets were of appropriate size (about 10 microns) and uniformly dispersed.

[0116] Example 6

[0117] This embodiment provides a method for preparing a lead-based metal halide perovskite single crystal nanosheet, comprising the following steps:

[0118] (1) PbCl2 and MACl (wherein, MA + CH3NH3 + ) was dissolved in DMSO and stirred at room temperature until fully dissolved to obtain a lead-based metal halide perovskite precursor solution with a concentration of 3 mol / L, which was filtered and placed in a small glass bottle (volume 50 mL);

[0119] The pore size of the filter head used for filtration is 0.5 μm;

[0120] (2) A small glass bottle (open, not sealed) containing a lead-based metal halide perovskite precursor solution was placed in a sealed large glass bottle (500 mL, 300 mL of anti-solvent (ether)). The large glass bottle was placed in a low-temperature environment of 0°C. After 56 hours, a complex of lead-based metal halide perovskite and an organic solvent was obtained, whose chemical formula is MAPbCl3·DMF.

[0121] (3) Treat the substrate (glass sheet) with a vacuum plasma treatment apparatus at a power of 50W for 1 minute to make the surface hydrophilic. Take 5mg of the complex of lead-based metal halide perovskite and organic solvent and place it on the treated substrate (area 10cm 2 ) (Calculation shows that the mass ratio of the complex of lead-based metal halide perovskite and organic solvent to the area of the treated substrate is 0.8 mg / cm 2 ) and placed on top of it another substrate (glass sheet) of the same area that had been plasma-treated using the same process. By applying pressure (0.8N) between the two substrates, the spacing between them was controlled. The complex of the lead-based metal halide perovskite and the organic solvent gradually decomposed, forming a saturated solution of the lead-based metal halide perovskite. After 2 minutes (this process was observed in real time and photographed), at a temperature of 35°C and a pressure of 1 atmosphere, as the organic solvent evaporated, a lead-based metal halide perovskite single crystal nanosheet was formed between the two substrates.

[0122] Figure 11 This is a diagram of the growth process of lead-based metal halide perovskite single crystal nanosheets MAPbCl3. As can be seen from the figure, white needle-shaped crystals (MAPbCl3·DMF) gradually grow into lead-based metal halide perovskite single crystal nanosheets (MAPbCl3).

[0123] Example 7

[0124] This embodiment provides a method for preparing a lead-based metal halide perovskite single crystal nanosheet, comprising the following steps:

[0125] (1) PbCl2 and MABr (wherein, MA + CH3NH3 + ) was dissolved in DMF and stirred at room temperature until fully dissolved to obtain a lead-based metal halide perovskite precursor solution with a concentration of 5 mol / L, which was filtered and placed in a small glass bottle (volume 50 mL);

[0126] The pore size of the filter head used for filtration is 0.5 μm;

[0127] (2) A small glass bottle (open, not sealed) containing a lead-based metal halide perovskite precursor solution is placed in a sealed large glass bottle (volume 500 mL, anti-solvent volume 240 mL) containing an anti-solvent (ether), and the large glass bottle is placed in a low-temperature environment of 5°C. After 24 hours, a complex of lead-based metal halide perovskite and an organic solvent is obtained.

[0128] (3) Treat the substrate (glass sheet) with a vacuum plasma treatment apparatus at a power of 350W for 1 minute to make the surface hydrophilic. Place 40mg of the complex of lead-based metal halide perovskite and organic solvent on the treated substrate (area 50cm 2 ) (Calculation shows that the mass ratio of the complex of lead-based metal halide perovskite and organic solvent to the area of the treated substrate is 0.8 mg / cm 2 ) and placed on top of it another substrate (glass sheet) of the same area that had been plasma-treated using the same process. By applying 1N of pressure between the two substrates, the spacing between them was controlled. The complex of the lead-based metal halide perovskite and the organic solvent gradually decomposed, forming a saturated solution of the lead-based metal halide perovskite. After 2 minutes (this process was observed and photographed in real time), at a temperature of 35°C and a pressure of 1 atmosphere, as the organic solvent evaporated, a lead-based metal halide perovskite single crystal nanosheet was formed between the two substrates.

[0129] Figure 10 is an optical microscope image of the lead-based metal halide perovskite single crystal nanosheet in this embodiment.

[0130] The applicant states that the present invention is intended to illustrate the detailed methods of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed methods, that is, it does not mean that the present invention must rely on the above-described detailed methods in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for various raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing perovskite single crystal nanosheets, characterized in that: The method comprises the following steps: (1) Mixing a raw material of a B-site cation, a raw material of an A-site cation, and an organic solvent to obtain a perovskite precursor solution; (2) contacting and reacting the perovskite precursor solution described in step (1) with an antisolvent to obtain a complex of perovskite and an organic solvent; (3) placing the complex of the perovskite and the organic solvent on a first substrate, applying pressure to the complex of the perovskite and the organic solvent to decompose it, obtaining a saturated perovskite solution, and removing the organic solvent to obtain the perovskite single crystal nanosheet; The method of applying pressure to the complex of perovskite and organic solvent in step (3) comprises: covering a side of a first substrate having the complex of perovskite and organic solvent with a second substrate, and applying pressure between the first substrate and the second substrate so that the complex of perovskite and organic solvent is pressurized; The first substrate and / or the second substrate is subjected to a hydrophilic treatment before use, wherein the hydrophilic treatment is performed by vacuum plasma treatment; The thickness of the perovskite single crystal nanosheet is 50-1000 nm, and the lateral size of the perovskite single crystal nanosheet is 1-50 μm.

2. The method according to claim 1, characterized in that The raw material of the B-site cation in step (1) is at least one of lead halide, tin halide or bismuth halide.

3. The method according to claim 2, characterized in that The raw material of the B-site cation is at least one of PbCl2, PbBr2, PbI2, SnCl2, SnBr2, SnI2, BiCl2, BiBr2 or BiI2.

4. The method according to claim 1, wherein The raw material of the A-site cation in step (1) is an organic halide and / or an inorganic halide.

5. The method according to claim 4, characterized in that The raw material of the A-site cation is at least one of MACl, MABr, MAI, FACl, FABr, FAI, CsCl, CsBr, CsI, RbCl, RbBr or RbI.

6. The method according to claim 1, wherein The mixing in step (1) is carried out at room temperature and is accompanied by stirring.

7. The method according to claim 1, characterized in that The concentration of the perovskite precursor solution in step (1) is 0.5~5 mol / L.

8. The method according to claim 1, characterized in that The perovskite precursor solution in step (1) is filtered, and the pore size of the filter component is 0.2-0.5 μm.

9. The method according to claim 1, characterized in that The method of contacting and reacting the perovskite precursor solution of step (1) with an antisolvent in step (2) comprises: (a) placing the perovskite precursor solution described in step (1) in an open first container; (b) placing the first container into a second container containing the anti-solvent and sealing the container; (c) placing the second container in a low-temperature environment for a period of time to obtain a complex of the perovskite and the organic solvent.

10. The method according to claim 1, characterized in that The anti-solvent comprises at least one of ether, chlorobenzene, toluene, anisole or dichloromethane.

11. The method according to claim 9, characterized in that The temperature of the low temperature environment is -10~10℃.

12. The method according to claim 9, characterized in that The period of time is 12 to 72 hours.

13. The method according to claim 1, wherein During the vacuum plasma treatment, the power is 50-500W and the time is 1-10 minutes.

14. The method according to claim 1, wherein The amount of the complex of perovskite and organic solvent used satisfies: the ratio of the mass of the complex of perovskite and organic solvent to the area of the first substrate is (0.1-1) mg / 1 cm 2 .

15. The method according to claim 1, wherein The magnitude of the applied pressure is 0.1~1N.

16. The method according to claim 1, characterized in that After applying pressure, let it stand for 3 to 10 minutes.

17. The method according to claim 1, wherein The temperature for removing the organic solvent is 20-40°C.

18. The method according to claim 1, wherein The pressure for removing the organic solvent is one atmosphere.

19. A perovskite single crystal nanosheet prepared by the method according to any one of claims 1 to 18, characterized in that: The thickness of the perovskite single crystal nanosheet is 50-1000 nm, and the lateral size of the perovskite single crystal nanosheet is 1-50 μm.

20. A short-wave infrared light detector, characterized in that: The short-wave infrared light detector includes an electrode and a perovskite single crystal nanosheet located on the surface of the electrode. The electrode includes a first electrode and a second electrode arranged side by side and spaced apart. A channel is formed between the first electrode and the second electrode, and only a single perovskite single crystal nanosheet exists in the channel.

21. A method for preparing a short-wave infrared light detector according to claim 20, characterized in that: The method comprises the following steps: Taking a substrate having a perovskite single crystal nanosheet on its surface, using a transfer platform, pressing a transfer film onto a selected single perovskite single crystal nanosheet, so that the transfer film and the single perovskite single crystal nanosheet are in contact, and then lifting the transfer film to obtain a transfer film with the perovskite single crystal nanosheet attached to its surface; The transfer film is pressed onto a substrate having electrodes on its surface, wherein the electrodes include a first electrode and a second electrode arranged opposite to each other, and only a single perovskite single crystal nanosheet exists between the first electrode and the second electrode, thereby obtaining the short-wave infrared light detector.

22. The method for preparing a short-wave infrared light detector according to claim 21, characterized in that: The distance between the first electrode and the second electrode is 1-100 μm.

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