Single-crystal single-domain perovskite thin film and remote epitaxial growth method and application thereof

Abstract

The invention provides a single-crystal single-domain perovskite thin film and a remote epitaxial growth method and application thereof. The remote epitaxial growth method comprises the following steps: in a chemical vapor deposition system, placing a substrate covered with a graphene thin film in a downstream low-temperature region, placing perovskite powder in a heating source region, carrying out heat treatment, epitaxially growing the single-crystal single-domain perovskite thin film on the surface of the graphene thin film, and then stripping the single-crystal single-domain perovskite thin film. The remote epitaxial growth method provided by the invention is simple in process, the high-quality single-crystal single-domain perovskite thin film capable of being transferred in a lossless manner can be obtained, and the single-crystal single-domain perovskite thin film has no crystal boundary, has the characteristics of single-crystal-level flatness, sub-wavelength thickness and large-area uniform luminescence, is beneficial to integration with a nano photonics structure, and is suitable for large-scale production. Therefore, the interaction between light and substances is enhanced, and a plurality of light-emitting dimensions such as direction, polarization, phase and orbital angular momentum are controlled. Therefore, the invention lays a material science foundation for the nano light-emitting device.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor nanomaterials, and in particular relates to a single-crystal single-domain perovskite film and a remote epitaxial growth method and application thereof. Background Art

[0002] Metal halide perovskite is a promising semiconductor material with advantages such as strong bandgap tunability and long carrier lifetime, so it can be used to prepare high-performance optoelectronic devices such as solar cells, light-emitting diodes, field-effect transistors, lasers and photodetectors. Compared with polycrystalline perovskites, single-crystal perovskites have orders of magnitude lower defect density suppression capabilities, significantly improved carrier mobility, and are easy to prepare high-performance optoelectronic devices.

[0003] Epitaxy is a technique for growing single-crystalline thin films by lattice matching and plays an important role in the semiconductor industry. Nowadays, epitaxy strategies have been introduced into the perovskite system to grow single-crystalline thin films for device applications. However, previous methods such as liquid-phase processed homoepitaxy, van der Waals epitaxy, and atomic heteroepitaxy are limited by moderate grain sizes and / or unavoidable material damage during the transfer process.

[0004] Therefore, there is an urgent need to provide a new epitaxial growth method for single-crystal single-domain perovskite films. Summary of the invention

[0005] In view of the deficiencies of the prior art, the object of the present invention is to provide a single-crystal single-domain perovskite film and its remote epitaxial growth method and application. The remote epitaxial growth method provided by the present invention has a simple process, and can obtain a high-quality, losslessly transferable single-crystal single-domain perovskite film. The single-crystal single-domain perovskite film has no grain boundaries, single-crystal flatness, sub-wavelength thickness, and large-area uniform luminescence characteristics, which is conducive to its integration with nanophotonic structures (such as resonant metasurfaces and photonic crystals), thereby achieving the enhancement of "light-matter interaction" and the manipulation of multiple luminescence dimensions such as direction, polarization, phase, and orbital angular momentum. Therefore, the present invention lays a material science foundation for nano-luminescent devices.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a remote epitaxial growth method of a single-crystal single-domain perovskite film, the remote epitaxial growth method comprising the following steps:

[0008] In a chemical vapor deposition system, a substrate covered with a graphene film is placed in a downstream low-temperature zone, and perovskite powder is placed in a heating source zone for heat treatment, and the single-crystal single-domain perovskite film is epitaxially grown on the surface of the graphene film, and then peeled off.

[0009] The remote epitaxial growth method provided by the present invention can obtain a high-quality, losslessly transferable single-crystal single-domain perovskite film, which has no grain boundaries, single-crystal-level flatness, sub-wavelength thickness, and large-area uniform luminescence characteristics, which is conducive to its integration with nanophotonic structures (such as resonant metasurfaces and photonic crystals), thereby achieving the enhancement of "light-matter interaction" and the manipulation of multiple luminescence dimensions such as direction, polarization, phase, and orbital angular momentum. Therefore, the present invention lays a material foundation for nano-luminescent devices.

[0010] The remote epitaxial growth method provided by the present invention has the advantages of simple process, universal applicability, etc.

[0011] It should be noted that the purpose of stripping is to remove the substrate covered with the graphene film to obtain a single-crystal single-domain perovskite film that can be used to prepare perovskite solar cells. At the same time, the stripped substrate covered with the graphene film can be reused.

[0012] Preferably, the graphene film covering method includes a wet transfer method or a substrate surface direct growth method.

[0013] Preferably, the specific steps of the wet transfer method include:

[0014] A transfer medium is coated on the graphene side surface of a graphene copper foil, and then the copper foil is etched away to obtain a transfer medium covered with a single-molecule graphene layer. The transfer medium covered with the single-molecule graphene layer is then transferred to the surface of a sapphire substrate, and the transfer medium is removed to obtain a sapphire substrate covered with a graphene film.

[0015] Preferably, the transfer medium comprises a polymethyl methacrylate (PMMA) film.

[0016] Preferably, during the etching process, the etching solution used includes FeCl3 solution.

[0017] Preferably, the substrate is made of sapphire.

[0018] Preferably, the graphene film is a single-molecule graphene layer.

[0019] Preferably, cooling is performed after the heat treatment is completed.

[0020] Preferably, the temperature after cooling is room temperature.

[0021] The present invention does not limit the specific temperature of the room temperature. For example, it can be 25±5°C, such as 20°C, 25°C or 30°C.

[0022] Preferably, the chemical formula of the perovskite powder is ABX3, wherein A includes any one or a combination of at least two of formamidinium ions, methylamine ions or cesium ions, B includes lead ions, and X is a halogen ion, for example, CsPbBr3 or CsPbCl3.

[0023] Preferably, the preparation method of the perovskite powder comprises a liquid phase synthesis method.

[0024] Preferably, the specific steps of the liquid phase synthesis method include: mixing a halide solution containing a B-site cation and a halide solution containing an A-site cation, and reacting to obtain a precipitate with a general chemical formula of ABX3.

[0025] Preferably, the heat treatment process is a gradient temperature control process.

[0026] In the present invention, the thermal treatment is performed in a gradient temperature control manner, which helps to fully heat the perovskite powder and accurately control the nucleation and growth rates of the perovskite film.

[0027] Preferably, the gradient temperature control process includes primary heat treatment, secondary heat treatment and tertiary heat treatment.

[0028] Preferably, the temperature of the primary heat treatment is 100-200°C, for example, it can be 100°C, 120°C, 140°C, 160°C, 180°C or 200°C, and the insulation time is 20-30min, for example, it can be 20min, 22min, 24min, 26min, 28min or 30min.

[0029] Preferably, the temperature of the secondary heat treatment is 250-350°C, for example, 250°C, 275°C, 300°C, 325°C or 350°C, etc., and the holding time is 5-15min, for example, 5min, 10min or 15min, etc.

[0030] Preferably, the temperature of the three-stage heat treatment is 560-640°C, for example, it can be 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C or 640°C, and the insulation time is 10-40min, for example, it can be 10min, 20min, 30min or 40min.

[0031] Preferably, during the heat treatment, the carrier gas of the gas phase perovskite includes an inert gas.

[0032] Preferably, the inert gas comprises nitrogen and / or argon.

[0033] Preferably, the flow rate of the inert gas is 25-30 sccm, for example, 25 sccm, 26 sccm, 27 sccm, 28 sccm, 29 sccm or 30 sccm.

[0034] In the present invention, if the flow rate of the inert gas is too small, the film growth rate is too slow, affecting the film preparation efficiency; if the flow rate of the inert gas is too large, the film tends to grow into a multi-layer polycrystalline state with poor crystallinity.

[0035] Preferably, the specific steps of peeling include:

[0036] A sacrificial layer and a release layer are sequentially coated on the surface of a single-crystal single-domain perovskite film, so that the single-crystal single-domain perovskite film is released from a substrate covered with a single-molecule graphene film, and then heated and the sacrificial layer is removed to obtain an independent single-crystal single-domain perovskite film.

[0037] The transfer method provided by the present invention can obtain an independent lossless film without destroying the chemical bond between the single crystal single domain perovskite film and the substrate.

[0038] In the present invention, the purpose of heating is to release the single crystal single domain perovskite film from the stripping layer.

[0039] Preferably, the sacrificial layer comprises a PC (polycarbonate) film.

[0040] Preferably, the material of the release layer includes polydimethylsiloxane (PDMS).

[0041] It should be noted that, by utilizing the viscosity of polydimethylsiloxane, the single-crystal single-domain perovskite film can be released from a substrate covered with a single-molecule graphene film.

[0042] Preferably, the heating temperature is 70-90°C, such as 70°C, 80°C or 90°C, etc., and the heating time is 10-30 min, such as 10 min, 20 min or 30 min, etc.

[0043] Preferably, the method for removing the sacrificial layer comprises a solvent dissolution method.

[0044] Preferably, the solvent dissolution method comprises: using a solvent that can dissolve the sacrificial layer to dissolve and remove the sacrificial layer.

[0045] Preferably, the method comprises the following steps:

[0046] (1) coating a transfer medium on the graphene side surface of a graphene copper foil, then etching and removing the copper foil to obtain a transfer medium covered with a single-molecule graphene layer, then transferring the transfer medium covered with the single-molecule graphene layer to the surface of a sapphire substrate, removing the transfer medium, and obtaining a sapphire substrate covered with a single-molecule graphene film;

[0047] (2) synthesizing perovskite powder in liquid phase, then placing the perovskite powder in a heating source area of ​​a tube furnace, and placing the sapphire substrate covered with a single-molecule graphene film in a downstream low-temperature area of ​​the tube furnace;

[0048] (3) setting a gradient temperature control program for the heating source area, firstly raising the temperature from room temperature to 100-200°C for a primary heat treatment of 20-30 minutes; then raising the temperature to 250-350°C for a secondary heat treatment of 5-15 minutes; finally raising the temperature to 560-640°C for a tertiary heat treatment of 10-40 minutes, during the heat treatment, using an inert gas with a flow rate of 25-30 sccm as a carrier gas to transport the obtained gas phase perovskite to the downstream low temperature zone of the tubular furnace, so that a single crystal single domain perovskite film is epitaxially grown on the surface of the single molecule graphene film, cooling the tubular furnace after the heat treatment, and then peeling off the single crystal single domain perovskite film, the specific steps include:

[0049] A sacrificial layer and a release layer are sequentially coated on the surface of a single-crystal single-domain perovskite film, so that the single-crystal single-domain perovskite film is released from a substrate covered with a single-molecule graphene film, and then heated and the sacrificial layer is removed to obtain an independent single-crystal single-domain perovskite film.

[0050] In a second aspect, the present invention provides a single crystal single domain perovskite film, wherein the single crystal single domain perovskite film is prepared by the remote epitaxial growth method as described in the first aspect.

[0051] In a third aspect, the present invention provides a perovskite light-emitting diode, wherein the perovskite light-emitting diode comprises the single-crystal single-domain perovskite film as described in the second aspect;

[0052] The thickness of the single-crystal single-domain perovskite film is 100-300 nm, for example, 100 nm, 200 nm or 300 nm.

[0053] Preferably, the perovskite light-emitting diode comprises a conductive glass, a hole transport layer, a single-crystal single-domain perovskite film, an electron transport layer and a metal electrode layer which are stacked.

[0054] The present invention does not limit the type of conductive glass, and illustratively, it can be ITO (indium tin oxide) conductive glass or FTO (fluorine-doped tin oxide) conductive glass, etc.; the present invention does not limit the type of electron transport layer, and illustratively, it can be TPBi layer or B3PYMPM layer, etc.; the present invention does not limit the type of hole transport layer, and illustratively, it can be PEDOT:PSS or NiO x The present invention does not limit the type of the back electrode layer, and illustratively, it can be an Ag layer or an Al layer, etc.

[0055] In a fourth aspect, the present invention provides a photoelectric device, comprising the perovskite light emitting diode as described in the third aspect.

[0056] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes 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.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] (1) In the remote epitaxial growth method provided by the present invention, the perovskite first nucleates at multiple locations on the graphene film, then grows laterally, and finally merges into a single-crystal single-domain film without grain boundaries, high quality, and losslessly transferable, with single-crystal flatness, sub-wavelength thickness, and large-area uniform luminescence characteristics, which is conducive to its integration with nanophotonic structures (such as resonant metasurfaces and photonic crystals), thereby achieving the enhancement of "light-matter interaction" and the manipulation of multiple luminescence dimensions such as direction, polarization, phase, and orbital angular momentum. Therefore, the present invention lays a material foundation for nano-luminescent devices.

[0059] (2) The remote epitaxial growth method provided by the present invention has the advantages of simple process and universal applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a process flow chart for preparing the single-crystal single-domain perovskite film provided by the present invention.

[0061] Figure 2 This is a fluorescence microscope image of the single-crystal single-domain CsPbBr3 perovskite film prepared in Example 1 of the present invention.

[0062] Figure 3 This is an AFM height image of the single-crystal single-domain CsPbBr3 perovskite film prepared in Example 1 of the present invention.

[0063] Figure 4 This is an XRD curve diagram of the single-crystal single-domain CsPbBr3 perovskite film prepared in Example 1 of the present invention.

[0064] Figure 5 This is a transmission electron microscope image of the single-crystal single-domain CsPbBr3 perovskite film prepared in Example 1 of the present invention.

[0065] Figure 6 This is a selected area electron diffraction pattern of the single crystal single domain CsPbBr3 perovskite film prepared in Example 1 of the present invention.

[0066] Figure 7 This is a fluorescence microscope image of the single-crystal single-domain CsPbCl3 perovskite film prepared in Example 2 of the present invention.

[0067] Figure 8 This is an AFM height image of the single-crystal single-domain CsPbCl3 perovskite film prepared in Example 2 of the present invention.

[0068] Fig. 9 This is the XRD curve diagram of the single crystal single domain CsPbCl3 perovskite film prepared in Example 2 of the present invention.

[0069] Fig.10 This is a transmission electron microscope image of the single-crystalline single-domain CsPbCl3 perovskite film prepared in Example 2 of the present invention.

[0070] Fig.11 This is a selected area electron diffraction pattern of the single crystal single domain CsPbCl3 perovskite film prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0071] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0072] It should be noted that the room temperature below refers to 25°C.

[0073] Example 1

[0074] This embodiment provides a remote epitaxial growth method for a single-crystal single-domain perovskite film, and its process flow chart is as follows: Figure 1 As shown, the remote epitaxial growth method comprises the following steps:

[0075] (1) Spin-coating PMMA on the graphene side surface of the graphene copper foil, and then baking at 80° C. for 10 min, and then treating the other side surface of the graphene copper foil with oxygen plasma; then etching and removing the copper foil in a FeCl3 etching solution to obtain a PMMA layer covered with a single-molecule graphene layer, and then rinsing the PMMA layer covered with a single-molecule graphene layer in water and isopropanol for multiple times, while fixing it on the water surface by surface tension, and then transferring it to the surface of a pretreated sapphire substrate; finally, dissolving the PMMA layer in acetone to obtain a sapphire substrate covered with a single-molecule graphene film;

[0076] The pretreatment steps of the sapphire substrate include: sequentially using acetone, ethanol, and isopropanol solutions for ultrasonic treatment for 10 minutes each, and then drying with nitrogen gas after cleaning;

[0077] (2) liquid phase synthesis of CsPbBr3 perovskite powder, the specific steps comprising: dissolving PbBr2 powder (10 mmol, 3.67 g) in 8 mL of hydrobromic acid and stirring until completely dissolved, dissolving CsBr (10 mmol, 2.12 g) in 3 mL of water, and then adding the obtained CsBr aqueous solution dropwise to the HBr solution after PbBr2 was dissolved, to form an orange precipitate after the reaction; filtering the orange precipitate and washing it with ethanol, and then drying it in a vacuum oven at 60°C for 12 h;

[0078] Then, 150 mg of CsPbBr3 perovskite powder was placed in a quartz boat and placed in the heating source area of ​​a tube furnace, and the sapphire substrate covered with the single-molecule graphene film was placed in the downstream low-temperature area of ​​the tube furnace;

[0079] (3) Setting a gradient temperature control program for the heating source zone, firstly raising the temperature from room temperature to 150°C within 5 minutes for a primary heat treatment of 25 minutes, then raising the temperature to 300°C for a secondary heat treatment of 10 minutes, and then raising the temperature to 575°C for a tertiary heat treatment of 30 minutes. During the heat treatment, nitrogen with a flow rate of 30 sccm was used as a carrier gas to transport the obtained gas phase perovskite to the downstream low temperature zone of the tube furnace, so that the surface epitaxial growth of the single-molecule graphene film was 164 nm thick and 2×2 cm in area. 2 After the heat treatment, the tube furnace is cooled, and then the sapphire substrate covered with the single-molecule graphene film is peeled off. The specific steps include:

[0080] (a) polycarbonate and chloroform are mixed in a mass ratio of 0.06:1, and magnetically stirred for 15 minutes to obtain a polycarbonate solution; then 10 drops of the polycarbonate solution are dropped on a clean glass slide, and then another glass slide is placed on the surface of the glass slide on which the polycarbonate solution is dropped, and after quickly dragging across the surface, it is dried in a fume hood for 10 minutes to evaporate the chloroform, thereby obtaining a flexible PC film;

[0081] (b) The PC film and the PDMS layer are sequentially coated on the surface of the single-crystal single-domain perovskite film, and the single-crystal single-domain perovskite film is released from the substrate covered with the single-molecule graphene film by utilizing the viscosity of the PDMS, and then heated at 80°C for 20 minutes to release the single-crystal single-domain perovskite film from the PDMS layer, and finally the PC film is dissolved by chloroform to obtain an independent single-crystal single-domain perovskite film.

[0082] Figure 2 A fluorescence microscope image of the single-crystal single-domain CsPbBr3 perovskite film prepared in this embodiment is shown. It can be seen from the image that the surface of the perovskite film is smooth and the light emission is uniform and bright.

[0083] Figure 3 The AFM height image of the single-crystal single-domain CsPbBr3 perovskite film prepared in this embodiment is shown. It can be seen from the image that the surface of the perovskite film is flat, has no grain boundaries, and has uniform thickness.

[0084] Figure 4 , Figure 5 and Figure 6 The XRD curve diagram, transmission electron microscope diagram and selected area electron diffraction diagram of the single crystal single domain CsPbBr3 perovskite film prepared in this embodiment are respectively shown. It can be seen from the figures that the single crystal single domain CsPbBr3 perovskite film prepared in this embodiment has good crystal quality, consistent film orientation and single crystal properties.

[0085] Example 2

[0086] This embodiment provides a remote epitaxial growth method for a single-crystal single-domain perovskite film, the remote epitaxial growth method comprising the following steps:

[0087] (1) Spin-coating PMMA on the graphene side surface of the graphene copper foil, and then baking at 80° C. for 10 min, and then treating the other side surface of the graphene copper foil with oxygen plasma; then etching and removing the copper foil in a FeCl3 etching solution to obtain a PMMA layer covered with a single-molecule graphene layer, and then rinsing the PMMA layer covered with a single-molecule graphene layer in water and isopropanol for multiple times, while fixing it on the water surface by surface tension, and then transferring it to the surface of a pretreated sapphire substrate; finally, dissolving the PMMA layer in acetone to obtain a sapphire substrate covered with a single-molecule graphene film;

[0088] The pretreatment steps of the sapphire substrate include: sequentially using acetone, ethanol, and isopropanol solutions for ultrasonic treatment for 10 minutes each, and then drying with nitrogen gas after cleaning;

[0089] (2) liquid phase synthesis of CsPbCl3 perovskite powder, specifically comprising the following steps: dissolving PbCl2 powder (10 mmol, 2.78 g) in 8 mL of hydrobromic acid and stirring until completely dissolved, dissolving CsCl (10 mmol, 1.68 g) in 3 mL of water, and then adding the obtained CsCl aqueous solution dropwise to the HCl solution after PbCl2 was dissolved, to form a white precipitate after the reaction; filtering the white precipitate, washing it with ethanol, and drying it in a vacuum oven at 60°C for 12 h;

[0090] Then, 150 mg of CsPbCl3 perovskite powder was placed in a quartz boat and placed in the heating source area of ​​a tube furnace, and the sapphire substrate covered with the single-molecule graphene film was placed in the downstream low-temperature area of ​​the tube furnace;

[0091] (3) Setting a gradient temperature control program in the heating source zone, firstly raising the temperature from room temperature to 150°C within 5 minutes for a primary heat treatment of 25 minutes, then raising the temperature to 300°C for a secondary heat treatment of 10 minutes, and then raising the temperature to 640°C for a tertiary heat treatment of 40 minutes. At the same time, nitrogen with a flow rate of 30 sccm was used as a carrier gas to transport the obtained gas phase perovskite to the downstream low temperature zone of the tube furnace, so that the surface of the single-molecule graphene film was epitaxially grown with a thickness of 120 nm and an area of ​​2×2 cm 2 After the heat treatment, the tube furnace is cooled, and then the sapphire substrate covered with the single-molecule graphene film is peeled off. The specific steps include:

[0092] (a) polycarbonate and chloroform are mixed in a mass ratio of 0.06:1, and magnetically stirred for 15 minutes to obtain a polycarbonate solution; then 10 drops of the polycarbonate solution are dropped on a clean glass slide, and then another glass slide is placed on the surface of the glass slide on which the polycarbonate solution is dropped, and after quickly dragging across the surface, it is dried in a fume hood for 10 minutes to evaporate the chloroform, thereby obtaining a flexible PC film;

[0093] (b) The PC film and the PDMS layer are sequentially coated on the surface of the single-crystal single-domain perovskite film, and the single-crystal single-domain perovskite film is released from the substrate covered with the single-molecule graphene film by utilizing the viscosity of the PDMS, and then heated at 80°C for 20 minutes to release the single-crystal single-domain perovskite film from the PDMS layer, and finally the PC film is dissolved by chloroform to obtain an independent single-crystal single-domain perovskite film. Figure 7 A fluorescence microscope image of the single-crystal single-domain CsPbCl3 perovskite film prepared in this embodiment is shown. It can be seen from the image that the surface of the perovskite film is smooth and the light emission is uniform and bright.

[0094] Figure 8 The AFM height image of the single-crystal single-domain CsPbCl3 perovskite film prepared in this embodiment is shown. It can be seen from the image that the surface of the perovskite film is flat, has no grain boundaries, and has uniform thickness.

[0095] Fig. 9 , Fig.10 and Fig.11 The XRD curve, transmission electron microscope image and selected area electron diffraction image of the single-crystalline single-domain CsPbCl3 perovskite film prepared in this embodiment are shown. It can be seen from the figure that the single-crystalline single-domain CsPbCl3 perovskite film prepared in this embodiment has good crystal quality, consistent film orientation, and single crystal properties.

[0096] Example 3

[0097] This embodiment provides a remote epitaxial growth method for a single-crystal single-domain perovskite film, the remote epitaxial growth method comprising the following steps:

[0098] (1) Spin-coating PMMA on the graphene side surface of the graphene copper foil, and then baking at 80° C. for 10 min, and then treating the other side surface of the graphene copper foil with oxygen plasma; then etching and removing the copper foil in a FeCl3 etching solution to obtain a PMMA layer covered with a single-molecule graphene layer, and then rinsing the PMMA layer covered with a single-molecule graphene layer in water and isopropanol for multiple times, while fixing it on the water surface by surface tension, and then transferring it to the surface of a pretreated sapphire substrate; finally, dissolving the PMMA layer in acetone to obtain a sapphire substrate covered with a single-molecule graphene film;

[0099] The pretreatment steps of the sapphire substrate include: sequentially using acetone, ethanol, and isopropanol solutions for ultrasonic treatment for 10 minutes each, and then drying with nitrogen gas after cleaning;

[0100] (2) Synthesizing MAPbBr3 perovskite powder in liquid phase, the specific steps include: dissolving PbBr2 powder (10 mmol, 3.67 g) in 8 mL of hydrobromic acid and stirring until completely dissolved, dissolving MABr (10 mmol, 1.12 g) in 3 mL of water, and then adding the obtained MABr aqueous solution dropwise to the HBr solution after PbBr2 is dissolved, and forming a precipitate after the reaction; filtering the precipitate and washing it with ethanol, and then drying it in a vacuum oven at 60°C for 12 hours;

[0101] Then, 150 mg of MAPbBr3 perovskite powder was placed in a quartz boat and placed in the heating source area of ​​a tube furnace, and the sapphire substrate covered with the single-molecule graphene film was placed in the downstream low-temperature area of ​​the tube furnace;

[0102] (3) Setting a gradient temperature control program for the heating source zone, first raising the temperature from room temperature to 150°C within 5 minutes for a primary heat treatment of 25 minutes, then raising the temperature to 300°C for a secondary heat treatment of 10 minutes, and then raising the temperature to 500°C for a tertiary heat treatment of 20 minutes. At the same time, nitrogen with a flow rate of 25 sccm was used as a carrier gas to transport the obtained gas phase perovskite to the downstream low-temperature zone of the tube furnace, so that the surface of the single-molecule graphene film was epitaxially grown with a thickness of 230 nm and an area of ​​2×2 cm 2 After the heat treatment, the tube furnace is cooled, and then the sapphire substrate covered with the single-molecule graphene film is peeled off. The specific steps include:

[0103] (a) polycarbonate and chloroform are mixed in a mass ratio of 0.06:1, and magnetically stirred for 15 minutes to obtain a polycarbonate solution; then 10 drops of the polycarbonate solution are dropped on a clean glass slide, and then another glass slide is placed on the surface of the glass slide on which the polycarbonate solution is dropped, and after quickly dragging across the surface, it is dried in a fume hood for 10 minutes to evaporate the chloroform, thereby obtaining a flexible PC film;

[0104] (b) The PC film and the PDMS layer are sequentially coated on the surface of the single-crystal single-domain perovskite film, and the single-crystal single-domain perovskite film is released from the substrate covered with the single-molecule graphene film by utilizing the viscosity of the PDMS, and then heated at 80°C for 20 minutes to release the single-crystal single-domain perovskite film from the PDMS layer, and finally the PC film is dissolved by chloroform to obtain an independent single-crystal single-domain perovskite film.

[0105] Example 4

[0106] The difference between this embodiment and embodiment 1 is that the gradient temperature control program in step (3) is adjusted to directly increase the temperature to 575° C. and heat at a constant temperature for 65 minutes.

[0107] The rest of the preparation methods and parameters were the same as those in Example 1.

[0108] Example 5

[0109] The difference between this embodiment and embodiment 2 is that the gradient temperature control program in step (3) is adjusted to directly increase the temperature to 640° C. and heat at a constant temperature for 75 minutes.

[0110] The rest of the preparation methods and parameters were the same as those in Example 2.

[0111] The single crystal single domain perovskite films prepared in Example 2 and Example 5 are pure blue light films.

[0112] Example 6

[0113] The difference between this embodiment and embodiment 1 is that the flow rate of nitrogen in step (3) is 20 sccm.

[0114] The rest of the preparation methods and parameters were the same as those in Example 1.

[0115] Example 7

[0116] The difference between this embodiment and embodiment 1 is that the flow rate of nitrogen in step (3) is 40 sccm.

[0117] The rest of the preparation methods and parameters were the same as those in Example 1.

[0118] Comparative Example 1

[0119] The difference between this comparative example and Example 1 is that in step (2), the CsPbBr3 perovskite powder and the sapphire substrate covered with a single-molecule graphene film are placed in the same heating source area.

[0120] The rest of the preparation methods and parameters were the same as those in Example 1.

[0121] Comparative Example 2

[0122] This comparative example provides a method for preparing a perovskite film, and the preparation method comprises the following steps:

[0123] (1) dissolving perovskite in DMSO solvent to prepare a saturated solution;

[0124] (2) dropping the saturated solution onto the surface of a clean substrate, and then covering the clean substrate to obtain an assembled structure;

[0125] (3) placing the assembled structure in an oven at 45° C. to volatilize the solvent, so that the solution is supersaturated and crystallized. After the solvent is completely evaporated, the two substrates are disassembled to obtain a perovskite film.

[0126] Performance Testing

[0127] The perovskite light-emitting diode is prepared based on the perovskite film provided in the above-mentioned embodiments 1, 3-4, 6-7 and comparative examples 1-2, and the specific steps include:

[0128] (I) The PEDOT:PSS solution was spin-coated on a clean ITO glass at a rate of 4000 rpm for 60 s, and then annealed at 150 °C for 30 min to prepare a hole transport layer PEDOT:PSS;

[0129] (ⅠⅠ) The independent perovskite film provided in the above embodiment and comparative example is transferred to the hole transport layer, and then 35nm of electron transport layer TPBi and 100nm of metal electrode Al are sequentially evaporated on the surface of the perovskite film to obtain a perovskite light-emitting diode.

[0130] The photoelectric performance of the above-mentioned perovskite light-emitting diode was tested, and the testing method was as follows:

[0131] The electroluminescence efficiency measurement system of Xipu Optoelectronics was used to measure the electroluminescence efficiency (EQE), brightness and emission wavelength (the effective area of ​​the test was 3mm 2 , temperature 25℃).

[0132] The test results are shown in Table 1.

[0133] Table 1

[0134]

[0135]

[0136] analyze:

[0137] As can be seen from the above table, the remote epitaxial growth method provided by the present invention produces a single-crystal single-domain thin film that is free of grain boundaries, high-quality and losslessly transferable, has single-crystal-level flatness, sub-wavelength thickness and large-area uniform luminescence characteristics, which is conducive to its integrated integration with nanophotonic structures (such as resonant metasurfaces and photonic crystals), thereby achieving the enhancement of "interaction between light and matter" and the manipulation of multiple luminescence dimensions such as direction, polarization, phase and orbital angular momentum.

[0138] By comparing Example 1 with Example 4, it can be seen that the use of gradient temperature control is helpful to fully heat the perovskite powder, while accurately controlling the nucleation and growth rates of the perovskite film, so that the electroluminescent efficiency (EQE) and brightness of the perovskite light-emitting diode are significantly improved.

[0139] By comparing Example 1 with Examples 6-7, it can be seen that if the nitrogen flow rate is too low, the film growth rate will be too slow, affecting the film preparation efficiency, thereby reducing the electroluminescent efficiency (EQE) and brightness of the perovskite light-emitting diode; if the nitrogen flow rate is too high, the film will tend to grow into a multi-layer polycrystalline state with poor crystallinity, thereby reducing the electroluminescent efficiency (EQE) and brightness of the perovskite light-emitting diode.

[0140] By comparing Example 1 with Comparative Example 1, it can be seen that if the CsPbBr3 perovskite powder and the sapphire substrate covered with a single-molecule graphene film are placed in the same heating source area, the substrate will not be located in the low-temperature area for depositing the epitaxial film, and the epitaxial growth will fail.

[0141] From the comparison between Example 1 and Comparative Example 2, it can be seen that the epitaxial growth method provided by the prior art is prone to generate polycrystalline nuclei and simultaneously compete for growth during the crystal growth process, which is not conducive to the preparation of a single-domain single crystal thin film.

[0142] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A remote epitaxial growth method for a single-crystal single-domain perovskite film, characterized in that: The remote epitaxial growth method comprises the following steps: In a chemical vapor deposition system, a substrate covered with a graphene film is placed in a downstream low-temperature zone, and perovskite powder is placed in a heating source zone for heat treatment, and the single-crystal single-domain perovskite film is epitaxially grown on the surface of the graphene film, and then peeled off.

2. The remote epitaxial growth method according to claim 1, characterized in that: The graphene film covering method includes a wet transfer method or a substrate surface direct growth method; Preferably, the material of the substrate includes sapphire; Preferably, the graphene film is a single-molecule graphene layer.

3. The remote epitaxial growth method according to claim 1 or 2, characterized in that: The general chemical formula of the perovskite powder is ABX3, wherein A comprises any one or a combination of at least two of formamidinium ions, methylamine ions or cesium ions, B comprises lead ions, and X is a halogen ion; Preferably, the method for preparing the perovskite powder comprises a liquid phase synthesis method.

4. The remote epitaxial growth method according to any one of claims 1 to 3, characterized in that: The heat treatment process is a gradient temperature control process; Preferably, the gradient temperature control process includes primary heat treatment, secondary heat treatment and tertiary heat treatment.

5. The remote epitaxial growth method according to claim 4, characterized in that: The temperature of the primary heat treatment is 100-200°C, and the insulation time is 20-30min; Preferably, the temperature of the secondary heat treatment is 250-350°C, and the holding time is 5-15min; Preferably, the temperature of the three-stage heat treatment is 560-640° C., and the holding time is 10-40 min.

6. The remote epitaxial growth method according to any one of claims 1 to 5, characterized in that: During the heat treatment, the carrier gas of the gas phase perovskite includes an inert gas; Preferably, the inert gas comprises nitrogen and / or argon; Preferably, the flow rate of the inert gas is 25-30 sccm.

7. The remote epitaxial growth method according to any one of claims 1 to 6, characterized in that: The specific steps of peeling include: A sacrificial layer and a release layer are sequentially coated on the surface of the single-crystal single-domain perovskite film, so that the single-crystal single-domain perovskite film is released from the substrate covered with the graphene film, and then heated and the sacrificial layer is removed to obtain an independent single-crystal single-domain perovskite film; Preferably, the sacrificial layer comprises a PC film; Preferably, the material of the release layer includes polydimethylsiloxane.

8. The remote epitaxial growth method according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: (1) coating a transfer medium on the graphene side surface of a graphene copper foil, then etching and removing the copper foil to obtain a transfer medium covered with a single-molecule graphene layer, then transferring the transfer medium covered with the single-molecule graphene layer to the surface of a sapphire substrate, removing the transfer medium, and obtaining a sapphire substrate covered with a single-molecule graphene film; (2) synthesizing perovskite powder in liquid phase, then placing the perovskite powder in a heating source area of ​​a tube furnace, and placing the sapphire substrate covered with a single-molecule graphene film in a downstream low-temperature area of ​​the tube furnace; (3) setting a gradient temperature control program for the heating source area, firstly raising the temperature from room temperature to 100-200°C for a primary heat treatment of 20-30 minutes; then raising the temperature to 250-350°C for a secondary heat treatment of 5-15 minutes; finally raising the temperature to 560-640°C for a tertiary heat treatment of 10-40 minutes, during the heat treatment, using an inert gas with a flow rate of 25-30 sccm as a carrier gas to transport the obtained gas phase perovskite to the downstream low temperature zone of the tubular furnace, so that a single crystal single domain perovskite film is epitaxially grown on the surface of the single molecule graphene film, cooling the tubular furnace after the heat treatment, and then peeling off the single crystal single domain perovskite film, the specific steps include: A sacrificial layer and a release layer are sequentially coated on the surface of a single-crystal single-domain perovskite film, so that the single-crystal single-domain perovskite film is released from a substrate covered with a single-molecule graphene film, and then heated and the sacrificial layer is removed to obtain an independent single-crystal single-domain perovskite film.

9. A single crystal single domain perovskite film, characterized in that: The single crystal single domain perovskite film is prepared by the remote epitaxial growth method as described in any one of claims 1 to 8.

10. A perovskite light-emitting diode, characterized in that: The perovskite light-emitting diode comprises the single-crystal single-domain perovskite thin film as claimed in claim 9; The thickness of the single crystal single domain perovskite film is 100-300nm.

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