阅读说明：本技术 一种实现基于杂化铅基钙钛矿纳米片制备tem样品的方法 (Method for preparing TEM sample based on hybrid lead-based perovskite nanosheets ) 是由 王琳 仲净贤 朱超 何凯悦 于 2021-07-01 设计创作，主要内容包括：本发明公开一种实现制备杂化铅基钙钛矿纳米片TEM样品的方法,通过转移基于PDMS膜的卤化铅纳米片到TEM的多种类载网支持膜,进一步实现不同类型钙钛矿纳米片的生长制备,最后通过TEM,进行结构表征,可以研究样品内部的晶相分布。本发明提供的杂化铅基钙钛矿纳米片制备TEM样品的方法具有可精准定点转移、灵活普适、无水接触、可控性好、样品损伤小、重复性好、产量高、成本低等优点,对挖掘钙钛矿材料内部晶体结构,发现新物理机制,以及推广至其它不同类型钙钛矿材料都具有着重要的科学意义和应用价值。(The invention discloses a method for preparing a TEM sample of a hybrid lead-based perovskite nanosheet. The method for preparing the TEM sample by the hybrid lead-based perovskite nanosheets has the advantages of capability of accurate fixed-point transfer, flexibility, universality, no water contact, good controllability, small sample damage, good repeatability, high yield, low cost and the like, and has important scientific significance and application value for excavating the internal crystal structure of the perovskite material, discovering a new physical mechanism and popularizing the method for preparing the TEM sample by the hybrid lead-based perovskite nanosheets to other different types of perovskite materials.)

1. A method for preparing a TEM sample based on lead-based perovskite nanosheets is characterized by comprising the following steps:

(1) placing the uniformly stirred lead halide solution at a low temperature, mechanically stripping on an adhesive tape after crystals are separated out, slightly pressing the adhesive tape by directly using a window consisting of a PDMS film and a glass slide, and quickly lifting to obtain a PDMS-lead halide nanosheet based on the window of the glass slide;

(2) inverting the PDMS-lead halide nanosheet based on the glass slide window above a transfer platform, attaching the edge of a TEM grid supporting film to a substrate by using a high-temperature adhesive tape, placing the TEM grid supporting film based on the substrate below the transfer platform, and then transferring to obtain a thin-layer lead halide nanosheet based on the substrate-TEM grid supporting film;

(3) placing thin-layer lead halide nanosheets based on a silicon wafer substrate-TEM grid supporting film in a downstream growth area of a tube furnace, placing another halide precursor AX in an upstream evaporation area, pumping negative pressure, introducing low-flow-rate carrier gas, heating, and realizing preparation and further TEM structure characterization of perovskite nanosheets of different types through ion insertion.

2. The method for realizing preparation of a TEM sample based on lead-based perovskite nanosheets as claimed in claim 1, wherein: the lead halide in the step 1 meets PbX₂The general formula is shown in the specification, wherein Pb is a lead element, X is a halogen element, chlorine (Cl), bromine (B) or iodine (I).

3. The method for realizing preparation of a TEM sample based on lead-based perovskite nanosheets as claimed in claim 1, wherein: in the preparation method of the lead halide solution and the crystal precipitation in the step 1, the mass of lead halide powder is 5-20mg, and the volume of deionized water is 5-20ml, so that the lead halide powder is dissolved in the deionized water to reach the concentration of 0.25-4 mg/ml; the crystal precipitation temperature is 4-40 ℃, and the time is 1-72 h.

4. The method for realizing preparation of a TEM sample based on lead-based perovskite nanosheets as claimed in claim 1, wherein: the preparation method of the glass slide substrate-PDMS membrane window in the step 1 is characterized in that the size of the PDMS membrane is 5 x 5-10 x 10mm, firstly, the Plasma cleaning time of a single glass slide is 10-300s, and the window cleaning time of the preparation and transfer of the PDMS membrane and the glass slide is 3-30 s.

5. The method for realizing preparation of a TEM sample based on lead-based perovskite nanosheets as claimed in claim 1, wherein: step 2, the pasting area of the high-temperature adhesive tape is 0.5-5 mm; the substrate to which the TEM grid supporting film is attached includes silicon oxide/Silicon (SiO)₂/Si), quartz, sapphire, ITO or FTO; the size of the substrate is 7 × 7-15 × 15 mm; the TEM grid-supported film comprises a common carbon supported film, an ultrathin carbon supported film, a porous carbon supported film, a small-hole micro-grid carbon supported film, a common micro-grid carbon supported film and a copper-plated carbon supported filmA film or a molybdenum coated carbon support film.

6. The method for realizing preparation of a TEM sample based on lead-based perovskite nanosheets as claimed in claim 1, wherein: according to the preparation method of the step 2, when the PDMS film is in contact with and pressed by the TEM grid-supported film through the transfer platform, the heating time is 1-5min, and the heating temperature is from room temperature to 55-85 ℃.

7. The method for realizing preparation of a TEM sample based on lead-based perovskite nanosheets as claimed in claim 1, wherein: the halide precursor in the step 3 meets the general formula of AX, wherein A is alkylamine, aromatic amine or metal ions, and comprises Methylamine (MA), Formamidine (FA), Phenethylamine (PEA), Butylamine (BA) or Naphthylmethylamine (NMA), and X is a halogen element, and comprises chlorine (Cl), bromine (B) or iodine (I);

8. the method for realizing preparation of a TEM sample based on lead-based perovskite nanosheets as claimed in claim 1, wherein: the negative pressure in step 3 is 10^-2Pa-10⁴Pa。

9. The method for realizing preparation of a TEM sample based on lead-based perovskite nanosheets as claimed in claim 1, wherein: in the preparation method of the step 3, the carrier gas is argon gas or argon-hydrogen mixed gas, and the gas flow is 0sccm-1000 sccm.

10. The method for realizing preparation of a TEM sample based on lead-based perovskite nanosheets as claimed in claim 1, wherein: the heating temperature in the step 3 is 20-300 ℃, and the heating time is 5min-5 h.

Technical Field

The invention relates to a method for preparing a TEM sample by using a hybrid lead-based perovskite nanosheet, which is flexible, universal, small in sample damage and high in repeatability, and is beneficial to research on the internal structure, physical mechanism and device optimization of a metal halide perovskite material.

Background

In recent years, hybrid perovskite materials have attracted extensive attention in the photovoltaic field due to their unique optoelectronic properties. The perovskite nanosheet rises rapidly by virtue of novel characteristics, effectively combines the advantages of two-dimensional materials and hybrid perovskite, so that the two-dimensional perovskite not only has the advantages of high absorption and luminous efficiency of three-dimensional materials, flexible and adjustable band gap, bipolar transmission and the like, but also has the characteristics of strong quantum effect, interface regulation and control, micro-nano processing and the like, and is an essential functional layer material of micro-nano photoelectric devices.

However, the microscopic properties of hybrid perovskites are not well understood. The problems of inflexible sample preparation method and poor later operability of the hybrid perovskite in the aspect of the current internal structure exist. The method is mainly characterized in the following three aspects: 1) perovskites are relatively sensitive and have instability problems when exposed to the environment (e.g., ultraviolet light or moisture); 2) the perovskite is very sensitive to organic solvents and is easily influenced by other solvents in the process of preparing a sample, so that the research on the inherent crystalline phase of the perovskite is not facilitated; 3) the perovskite grows on the substrate, and the viscosity of the substrate is very large, which brings great inconvenience to TEM sample preparation. Therefore, it is necessary to develop a method for preparing a TEM sample from perovskite nanosheets, which facilitates research on the internal structure, physical mechanism and device application of the perovskite nanosheets.

At present, there are two main methods for preparing perovskite TEM, one is a solvent method, i.e. a perovskite concentrated solution is dispersed into an organic solvent, so that a carbon-supported membrane is used to support part of perovskite solute in the solution, and TEM test is performed. The method mainly aims at the inorganic perovskite quantum dot colloidal solution, and the organic-inorganic hybrid perovskite is more sensitive to an organic solvent, so the method is easy to damage the stability; another method is a cutting method, i.e., a perovskite sample is torn from a substrate onto a carbon support film, thereby performing a TEM test. The method mainly aims at the perovskite thin film, but the perovskite thin film generally has larger acting force with a substrate, the method needs certain dexterity, and other impurities are generally introduced in the preparation of the perovskite thin film, so that the research on the crystal phase structure of the perovskite is not facilitated. In consideration of various condition limitations of perovskite, the method for preparing the TEM sample by the high-quality hybrid lead-based perovskite nanosheet is flexible, universal, small in sample damage and good in repeatability, and is beneficial to research on the internal structure, the physical mechanism and device optimization of the perovskite material.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for preparing a TEM sample based on a hybrid lead-based perovskite nanosheet. The invention provides a method for preparing a TEM sample by using high-quality hybrid lead-based perovskite nanosheets, which is flexible, universal, small in sample damage and good in repeatability, and is beneficial to research on the internal structure, physical mechanism and device optimization of perovskite materials.

The technical scheme provided by the invention is as follows: a method for preparing a TEM sample based on a hybrid lead-based perovskite nanosheet is used for preparing a lead halide nanosheet or a hybrid lead-based perovskite nanosheet through a transfer post-treatment process, and the preparation method has the advantages of flexibility, universality, good controllability, good repeatability, high yield, low cost and the like. The method specifically comprises the following steps: (1) placing the uniformly stirred lead halide solution at a low temperature, mechanically stripping on an adhesive tape after crystals are separated out, slightly pressing the adhesive tape by directly using a window consisting of a PDMS film and a glass slide, and quickly lifting to obtain a PDMS-lead halide nanosheet based on the window of the glass slide; (2) inverting the PDMS-lead halide nanosheet based on the glass slide window above a transfer platform, attaching the edge of a TEM grid supporting film to a substrate by using a high-temperature adhesive tape, placing the TEM grid supporting film based on the substrate below the transfer platform, and then transferring to obtain a thin-layer lead halide nanosheet based on the substrate-TEM grid supporting film; (3) the thin-layer lead halide nanosheet based on the silicon wafer substrate-TEM grid-supported film is placed in a downstream growth area of a tube furnace, another halide precursor AX is placed in an upstream evaporation area, negative pressure is pumped out, heating is carried out, and through ion insertion, preparation of perovskite nanosheets of different types and further TEM structure characterization are achieved.

Preferably, in the method for preparing a TEM sample by using the hybrid lead-based perovskite nanosheet, the halide precursor satisfies the general formula AX, wherein a is alkylamine or (and) aromatic amine or (and) metal ion, including Methylamine (MA), Formamidine (FA), Phenethylamine (PEA), Butylamine (BA), and Naphthylmethylamine (NMA), and X is a halogen element, including chlorine (Cl), bromine (B), and iodine (I).

Preferably, in the method for preparing TEM sample by using the hybrid lead-based perovskite nanosheets, the lead halide meets PbX₂The general formula is shown in the specification, wherein Pb is a lead element, X is a halogen element, chlorine (Cl), bromine (B) and iodine (I).

Preferably, in the method for preparing the TEM sample by using the hybrid lead-based perovskite nanosheet, the mass of the lead halide powder is 5-20mg, and the volume of the deionized water is 5-20ml, so that the lead halide powder is dissolved in the deionized water to reach a concentration of 0.25-4 mg/ml.

Preferably, in the method for preparing the TEM sample by the hybrid lead-based perovskite nanosheet, the temperature for precipitating the lead halide solution crystal is 4-40 ℃ and the time is 1-72 h.

Preferably, in the method for preparing the TEM sample by the hybrid lead-based perovskite nanosheet, the PDMS membrane is 5 x 5-10 x 10mm in size, firstly, the single glass slide is cleaned for 10-300s by adopting Plasma, and the window cleaning time for preparation and transfer of the PDMS membrane and the glass slide is 3-30 s.

Preferably, in the method for preparing the TEM sample by the hybrid lead-based perovskite nanosheet, the substrate adhered to the TEM grid supporting film comprises silicon oxide/Silicon (SiO)₂Si), quartz, sapphire, ITO, FTO.

Preferably, in the method for preparing the TEM sample by the hybrid lead-based perovskite nanosheet, the size of the substrate adhered to the TEM grid-supported supporting film is 7 × 7-15 × 15 mm.

Preferably, in the method for preparing the TEM sample by using the hybrid lead-based perovskite nanosheet, the TEM grid-supported supporting film comprises a common carbon supporting film, an ultrathin carbon supporting film, a porous carbon supporting film, a small-hole micro-grid supporting film, a common micro-grid carbon supporting film, a copper-plated carbon supporting film and a molybdenum-plated carbon supporting film.

Preferably, the method for preparing the TEM sample by the hybrid lead-based perovskite nanosheet comprises the step of heating the PDMS membrane to 55-85 ℃ from room temperature for 1-5min by a transfer platform when the PDMS membrane is in contact with and pressed by a TEM grid supporting membrane.

Preferably, the hybrid lead-based calciumMethod for preparing TEM sample by using titanium ore nanosheets, wherein negative pressure is 10^-2Pa-10⁴Pa。

Preferably, in the method for preparing the TEM sample by using the hybrid lead-based perovskite nanosheet, the carrier gas is argon gas or argon-hydrogen mixed gas, and the gas flow is 0sccm-1000 sccm.

Preferably, the method for preparing the TEM sample by the hybrid lead-based perovskite nanosheets has the heating temperature of 20-300 ℃ and the heating time of 5min-5 h.

Advantageous effects

The invention discloses a method for preparing a TEM sample of a hybrid lead-based perovskite nanosheet, which can transfer lead halide nanosheets based on a PDMS (polydimethylsiloxane) film to various net-supported supporting films of a TEM, and then further realize growth preparation and structure characterization of perovskite nanosheets of different types, and comprises the following three parts: 1, obtaining a lead halide nanosheet on a PDMS substrate through low-temperature recrystallization; 2, directly transferring the lead halide nanosheets on the PDMS substrate to various grid supporting films of TEM through a transfer platform; and 3, placing the lead halide nanosheets based on the TEM grid-supported supporting film in a tubular furnace, and obtaining the lead-based perovskite nanosheets through full reaction of the lead halide nanosheets and a halide precursor, and then observing the internal structure of the lead-based perovskite nanosheets by adopting a TEM. The method for preparing the TEM sample based on the lead-based perovskite nanosheets, provided by the invention, has the advantages of capability of accurate fixed-point transfer, flexibility, universality, no water contact, good controllability, small sample damage, high repeatability, high yield, low cost and the like, and has important scientific significance and application value for excavating the internal crystal structure of the perovskite material, discovering a new physical mechanism and popularizing the method to other perovskite materials of different types.

The invention provides a method for TEM sample preparation by low-temperature recrystallization, PDMS membrane window accurate positioning transfer and tube furnace sintering aiming at the TEM sample preparation requirement of the research of the hybrid lead-based perovskite nano sheet, which is suitable for various perovskite and TEM grid-supported support membranes, has the advantages of flexibility, universality, good controllability, good repeatability, high yield, low cost and the like, and can promote the optimization research of the internal structure, the physical mechanism and the device of the perovskite nano sheet.

The invention has undergone a large number of experimental screens for the selection of PDMS membranes. When the sample is transferred, the windows respectively adopt PC, PPC and PDMS films, and the critical temperature of the viscosity of the PC film and the PPC film is higher than 100 degrees, even up to 200 degrees, which impairs the quality of the sample. In addition, when the PC film and the PPC film are used, a foaming organic solvent such as acetone is also required, but the organic solvent is also very harmful to the sample. And the viscosity critical temperature of the PDMS membrane is lower than 90 ℃, and secondary treatment of an organic solvent is not needed, so that the method is very suitable for TEM sample preparation of the hybrid lead-based perovskite nanosheet.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention in which:

FIG. 1 is a schematic diagram of the preparation of lead halide crystals by a low-temperature recrystallization method according to the present invention;

FIG. 2 is a schematic view of a PDMS membrane slide window prepared according to an implementation of the present invention;

fig. 3 is a schematic diagram of the implementation of the present invention for preparing PDMS-based lead halide nanosheets;

FIG. 4 is a schematic diagram of a TEM grid supporting film attached to a substrate;

FIG. 5 is a schematic diagram of a TEM grid support film for transferring lead halide nanosheets provided by the present invention;

FIG. 6 is a schematic diagram of preparation of TEM mesh-supported membrane-based perovskite nanosheets achieved by the present invention;

FIG. 7 shows a PbI substrate prepared from PDMS in example 1₂An optical photograph of the nanoplatelets;

FIG. 8 is a view showing a conventional carbon supporting film base PbI of example 1 according to the present invention₂And MAPbI₃Optical photo and photoluminescence spectra of the nanoplatelets;

FIG. 9 shows a conventional carbon-supporting film base PbI of example 1 according to the present invention₂And MAPbI₃TEM representation of the nanosheets;

FIG. 10 is a PbI ultrathin carbon supporting film base of example 2 provided by the present invention₂；

FIG. 11 shows a PbI-based copper-coated carbon support film of example 3 according to the present invention₂；

FIG. 12 is a molybdenum-coated carbon support film base NMA of example 4 provided by the present invention₂FA_n-1Pb_nI_3n+1；

FIG. 13 is a general micro-grid carbon support film base MA of example 5 provided by the present invention_xFA_1-xPbI₃And TEM representation;

Detailed Description

Example 1:

20mg of PbI₂Mixing the granules with 10ml of deionized water, stirring for 6h on a heating table at 92 ℃, and uniformly stirring PbI₂Placing the solution at 4 ℃ for 24 hours, extracting the solution onto an adhesive tape after crystals are precipitated, mechanically stripping the solution, directly lightly pressing the adhesive tape by using a window consisting of a 7 x 7mm PDMS film and a slide glass which is cleaned by Plasma for 300s, and quickly lifting the adhesive tape to obtain PDMS-PbI based on the window of the slide glass₂Washing the nanosheets for 20 s; PDMS-PbI based on glass slide window₂Inversely placing the nanosheets above a transfer platform, attaching the edges of the common carbon supporting film to 10 x 10mm silicon wafers by using a 1mm high-temperature adhesive tape, fixing the silicon wafers below the transfer platform, descending a window, setting the heating temperature to 80 ℃ after the window is attached to the common carbon supporting film, heating for 3min, keeping the temperature at 80 ℃ for 2min, and slowly lifting to obtain the thin-layer PbI based on the silicon wafer substrate-common carbon supporting film₂Nanosheets; thin layer PbI based on silicon wafer substrate-common carbon supporting film₂Placing the nano-sheet in the downstream growth zone of the tube furnace, placing halide precursor MAI in the upstream evaporation zone of the tube furnace, vacuumizing the tube furnace to make it less than 10⁴Pa vacuum atmosphere. Argon-hydrogen mixture (Ar (90%)/H) was introduced into the tube furnace at a flow rate of 50sccm₂(10%)). Heating the evaporation zone to 125 deg.C for 100 min, heating the growth zone to 90 deg.C for 200 min to allow the gas-phase MAI precursor to react withPbI₂The nano-sheet fully reacts to obtain the common carbon supporting film base MAPbI₃Perovskite nano-sheet, can further carry out TEM structural characterization.

Example 2:

16mg of PbI₂Mixing the granules with 10ml of deionized water, stirring for 6h on a heating table at 92 ℃, and uniformly stirring PbI₂Placing the solution at 20 ℃ for 30 hours, extracting the solution onto an adhesive tape after crystals are precipitated, mechanically stripping the solution, directly lightly pressing the adhesive tape by using a window consisting of a PDMS film with the size of 5 x 5mm and a slide glass which is cleaned by Plasma for 100s, and quickly lifting the adhesive tape to obtain PDMS-PbI based on the window of the slide glass₂Washing the nanosheets for 10 s; PDMS-PbI based on glass slide window₂Inversely placing the nanosheets above a transfer platform, attaching the edges of the ultrathin carbon supporting films to 7 x 7mm silicon wafers by using 0.5mm high-temperature adhesive tapes, fixing the silicon wafers below the transfer platform, after a window is attached to the carbon films, setting the heating temperature to be 60 ℃, raising the temperature for 2min, keeping the temperature at 60 ℃ for 1min, and slowly lifting the silicon wafers to obtain the thin layer PbI based on the silicon wafer substrate-ultrathin carbon supporting films₂Nanosheets; thin layer PbI based on silicon chip substrate-ultrathin carbon supporting film₂Placing the nano-sheet in the downstream growth zone of the tube furnace, placing halide precursor MAI in the upstream evaporation zone of the tube furnace, vacuumizing the tube furnace to make it less than 10⁴Pa vacuum atmosphere. Argon-hydrogen mixture (Ar (90%)/H) was introduced into the tube furnace at a flow rate of 50sccm₂(10%)). Heating the evaporation zone to 125 deg.C for 100 min, heating the growth zone to 90 deg.C for 200 min to allow the MAI precursor and PbI to be in vapor phase₂The nano-sheets fully react to obtain the ultrathin carbon supporting film base MAPbI₃Perovskite nano-sheet, can further carry out TEM structural characterization.

Example 3:

mixing 12mg of PbI₂Mixing the granules with 10ml of deionized water, stirring for 10h on a heating table at 92 ℃, and uniformly stirring PbI₂Standing the solution at 10 deg.C for 30 hr, separating out crystal, taking out on adhesive tape, mechanically peeling, lightly pressing the adhesive tape with window composed of 6 × 6mm PDMS film and 50s slide glass cleaned by Plasma, and quickly taking outObtaining PDMS-PbI based on the glass slide window₂Washing the nanosheets for 5 s; PDMS-PbI based on glass slide window₂Inversely placing the nanosheets above a transfer platform, attaching the edges of the copper-coated carbon supporting film to 8 x 8mm silicon wafers by using a 1mm high-temperature adhesive tape, fixing the silicon wafers below the transfer platform, after a window is attached to the carbon film, setting the heating temperature to be 70 ℃, raising the temperature for 3min, keeping the temperature at 80 ℃ for 2min, and slowly lifting the silicon wafers to obtain a thin layer PbI based on the silicon wafer substrate-copper-coated carbon supporting film₂Nanosheets; thin layer PbI based on silicon chip substrate-copper-coated carbon supporting film₂Placing the nano-sheet in the downstream growth zone of the tube furnace, placing halide precursors MAI and NMAI in the upstream evaporation zone of the tube furnace, vacuumizing the tube furnace to make them less than 10⁴Pa vacuum atmosphere. Argon-hydrogen mixture (Ar (90%)/H) was introduced into the tube furnace at a flow rate of 50sccm₂(10%)). Heating the evaporation zone to 125 deg.C for 100 min, heating the growth zone to 90 deg.C for 200 min to allow the MAI precursor and PbI to be in vapor phase₂The nano-sheets fully react to obtain a copper-plated carbon supporting film base MAPbI₃Perovskite nano-sheet, can further carry out TEM structural characterization.

Example 4:

mixing 12mg of PbI₂Mixing the granules with 10ml of deionized water, stirring for 10h on a heating table at 92 ℃, and uniformly stirring PbI₂Placing the solution at 10 ℃ for 30 hours, extracting the solution onto an adhesive tape after crystals are precipitated, mechanically stripping the solution, directly lightly pressing the adhesive tape by using a window consisting of a 6 x 6mm PDMS film and a slide glass which is cleaned by Plasma for 50s, and quickly lifting the adhesive tape to obtain PDMS-PbI based on the window of the slide glass₂Washing the nanosheets for 5 s; PDMS-PbI based on glass slide window₂Inversely placing the nanosheets above a transfer platform, attaching the edge of the molybdenum-plated carbon supporting film to an 8 x 8mm silicon wafer by using a 1mm high-temperature adhesive tape, fixing the silicon wafer below the transfer platform, attaching a window to the carbon film, setting the heating temperature to be 70 ℃, raising the temperature for 3min, keeping the temperature at 80 ℃ for 2min, and slowly lifting to obtain a thin layer PbI based on the silicon wafer substrate-molybdenum-plated carbon supporting film₂Nanosheets; thin layer PbI based on silicon wafer substrate-molybdenum-coated carbon supporting film₂Placing the nano-sheet in the downstream growth zone of the tube furnace, placing halide precursors NMAI and FAI in the upstream evaporation zone of the tube furnace, vacuumizing the tube furnace to make the volume of the tube furnace less than 10⁴Pa vacuum atmosphere. Argon gas was introduced into the tube furnace at a flow rate of 50 sccm. Heating the evaporation zone to 135 deg.C for 100 min, heating the growth zone to 90 deg.C for 200 min to allow the MAI precursor and PbI to be in vapor phase₂The nano-sheets fully react to obtain the molybdenum-plated carbon supporting film base NMA₂FA_{n- 1}Pb_nI_3n+1Perovskite nano-sheet, can further carry out TEM structural characterization.

Example 5:

mixing 10mg of PbI₂Mixing the granules with 10ml of deionized water, stirring for 20h on a heating table at 92 ℃, and uniformly stirring PbI₂Placing the solution at 20 ℃ for 30 hours, extracting the solution onto an adhesive tape after crystals are precipitated, mechanically stripping the solution, directly lightly pressing the adhesive tape by using a window consisting of a 6 x 6mm PDMS film and a slide glass which is cleaned by Plasma for 50s, and quickly lifting the adhesive tape to obtain PDMS-PbI based on the window of the slide glass₂Washing the nanosheets for 5 s; PDMS-PbI based on glass slide window₂Inversely placing the nanosheets above a transfer platform, attaching the edges of the common micro-grid carbon supporting film to 8 x 8mm silicon wafers by using a 1mm high-temperature adhesive tape, fixing the silicon wafers below the transfer platform, attaching a window to the carbon film, setting the heating temperature to be 70 ℃, raising the temperature for 3min, keeping the temperature at 70 ℃ for 2min, and slowly lifting to obtain a thin layer PbI based on the silicon wafer substrate-the common micro-grid carbon supporting film₂Nanosheets; thin layer PbI based on silicon chip substrate-common micro-grid carbon supporting film₂Placing the nano-sheet in the downstream growth zone of the tube furnace, placing halide precursors MAI and FAI in the upstream evaporation zone of the tube furnace, vacuumizing the tube furnace to make the vapor reach less than 10%⁴Pa vacuum atmosphere. Argon-hydrogen mixture (Ar (90%)/H) was introduced into the tube furnace at a flow rate of 50sccm₂(10%)). The evaporation zone was heated to 145 ℃ for 100 minutes and the growth zone to 95 ℃ for 200 minutes to allow the vapor phase of the MAI and FAI precursors to react with PbI₂The nano-sheets fully react to obtain the common micro-grid carbon supporting film matrix MA_xFA_1-xPbI₃Perovskite nanoplatelets ofFurther TEM structural characterization was performed.

Comparative example 1:

mixing 10mg of PbI₂Mixing the granules with 10ml of deionized water, stirring for 20h on a heating table at 92 ℃, and uniformly stirring PbI₂Placing the solution at 20 ℃ for 30 hours, extracting the solution onto an adhesive tape after crystals are precipitated, mechanically stripping the solution, directly lightly pressing the adhesive tape by using a window consisting of a 6 x 6mm PDMS film and a slide glass which is cleaned by Plasma for 50s, and quickly lifting the adhesive tape to obtain PDMS-PbI based on the window of the slide glass₂Washing the nanosheets for 5 s; PDMS-PbI based on glass slide window₂Inversely placing the nanosheets above a transfer platform, attaching the edges of the common carbon supporting film to 8 x 8mm silicon wafers by using a 1mm high-temperature adhesive tape, fixing the silicon wafers below the transfer platform, after a window is attached to the carbon film, setting the heating temperature to be 100 ℃, raising the temperature for 3min, keeping the temperature at 100 ℃ for 2min, and slowly lifting the heated silicon wafers to obtain a thin layer PbI based on the silicon wafer substrate-the common carbon supporting film₂Nanosheets, but PbI₂The quality of the nanosheet is deteriorated, and the PL strength is weakened; thin layer PbI based on silicon wafer substrate-common carbon supporting film₂Placing the nano-sheet in the downstream growth zone of the tube furnace, placing halide precursor MAI in the upstream evaporation zone of the tube furnace, vacuumizing the tube furnace to make it less than 10⁴Pa vacuum atmosphere. Argon-hydrogen mixture (Ar (90%)/H) was introduced into the tube furnace at a flow rate of 50sccm₂(10%)). Heating the evaporation zone to 125 ℃ for 100 minutes, heating the growth zone to 95 ℃ for 200 minutes to allow the MAI precursor and PbI to be in vapor phase₂The nano-sheet fully reacts to obtain the common carbon supporting film base MAPbI₃Perovskite nanosheets, but PL of perovskite also becomes weaker, further TEM structural characterization is performed, and perovskite is also found to be more easily degraded.

And (4) conclusion: the window heating temperature of the transfer process cannot exceed 100 ℃, and the quality of the sample can be damaged by too high temperature, which is not beneficial to researching the intrinsic property of the sample.

Comparative example 2:

mixing 10mg of PbI₂Mixing the granules with 10ml of deionized water, stirring for 20h on a heating table at 92 ℃, and uniformly stirring PbI₂The solution is at 20 deg.CStanding for 30 hours, after crystals are precipitated, extracting the crystals onto an adhesive tape, mechanically stripping the crystals, directly lightly pressing the adhesive tape by using a window consisting of a PDMS film with the size of 6 x 6mm and a glass slide which is cleaned by Plasma for 50s, and quickly lifting the adhesive tape to obtain PDMS-PbI based on the window of the glass slide₂Washing the nanosheets for 5 s; PDMS-PbI based on glass slide window₂The method comprises the steps of inversely placing a nanosheet above a transfer platform, using a 1mm high-temperature adhesive tape to attach the edge of a common carbon supporting film to a 8 x 8mm silicon chip, fixing the silicon chip below the transfer platform, attaching a window to a carbon film, setting the heating temperature to be 40 ℃, heating for 3min, keeping the temperature at 40 ℃ for 2min, slowly lifting, finding that no sample exists on the common carbon supporting film, and indicating that the sample cannot fall off from a PDMS film when the transfer temperature is too low, so that the sample cannot be obtained on the common carbon supporting film, and subsequently, the perovskite preparation and TEM representation cannot be performed.

And (4) conclusion: the window heating temperature during the transfer process is below 50 ℃, which can result in the sample not falling to the quality of the carbon support film and not being available for subsequent study.

It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.