CN113106535B - Preparation method of two-dimensional perovskite single crystal - Google Patents

Abstract

The invention discloses a preparation method of a two-dimensional perovskite single crystal. The invention uses a liquid level confinement method to grow the single crystal, and the growth of the single crystal in the thickness direction is suppressed by the thickness of the precursor solvent layer itself. The direction of the liquid level is limited without affecting the growth of the crystal in other directions, and a large-sized perovskite single crystal with a controllable thickness can be obtained. Second, confinement of its thickness by the liquid surface rather than the substrate reduces the contact of the perovskite single crystal with the substrate, thereby reducing the defects of the single crystal. In addition, the precursor liquid can diffuse into the limiting phase solvent and volatilize, increasing the concentration of the precursor liquid and promoting growth. Compared with the temperature inversion growth method, the required temperature is lower and the growth is slow, which ensures the crystal quality and makes the prepared photodetector The surface trap density is lower, showing excellent optoelectronic properties. The ultrathin perovskite single crystal has good application prospects in the field of optoelectronics.

Description

A kind of preparation method of two-dimensional perovskite single crystal

technical field

The invention belongs to the field of semiconductor optoelectronic materials, and relates to a preparation method and optoelectronic properties of a two-dimensional perovskite single crystal, in particular to the growth of a plane perovskite single crystal with large surface area to volume ratio, large area and high quality method.

Background technique

Perovskite materials have been extensively studied due to their excellent photophysical properties, such as tunable optical properties, large absorption coefficient, low defect density, and long carrier diffusion length. These properties give them great potential in solar cells, light-emitting diodes, lasers, and photodetectors, among others. It is one of the hotspots at home and abroad to study the influence of the size, structure and composition of nanostructures on the properties of nanomaterials, and to design nanostructures with new or enhanced properties and application prospects. Based on the dimensionality reduction of three-dimensional hybrid metal halide perovskites to improve their optoelectronic properties, a large number of literatures have studied the application of low-dimensional perovskites in photodetectors, while two-dimensional perovskites have exciting properties. It has attracted much attention due to its special properties such as high molecular binding energy, high photoluminescence quantum yield (PLQY), high crystallinity, and good stability. Defects in 2D perovskites mainly depend on their composition, diameter or thickness, growth and processing methods, and these factors greatly affect the performance of 2D materials. While some perovskites whose thicknesses do not meet the original definition of 2D materials (thickness less than 100 nm) are less than the carrier diffusion length due to the disappearance of grain boundaries, and most importantly, their properties vary with thickness. changes also occur, so these single crystals with large surface-to-volume ratios are also of interest.

At present, the growth methods of ultra-thin perovskite single crystals mainly include spin coating, chemical vapor deposition, Top-down, and space confinement. However, these methods have their own defects. For example, the thickness of single crystals prepared by spin coating and chemical vapor deposition methods can reach several tens of nanometers, but the lateral size is difficult to reach millimeters; Cut to below 100 µm; the space limitation method requires two substrates to limit the crystal growth space. Defects on the substrate can easily affect the quality of single crystals, and it is difficult to prepare crystals below 100 µm.

The single crystal prepared by the existing method usually has a small area or a large thickness. The invention provides a two-dimensional perovskite single crystal and a growth method thereof. The growth of the single crystal in the thickness direction is restricted by the liquid-liquid interface, and an ABX ₃ single crystal with a small thickness and a large area is obtained.

SUMMARY OF THE INVENTION

The invention provides a preparation method of a two-dimensional perovskite single crystal, which has the characteristics of simple preparation, low cost, small thickness, large area, no need for an anti-solvent, and high crystal quality, and makes up for the deficiencies in the prior art.

The experimental scheme of the present invention is shown in the following steps:

A method for preparing a two-dimensional perovskite single crystal, characterized in that a two-dimensional ABX ₃ perovskite semiconductor material is prepared by a liquid-liquid phase confinement method, and the upper surface of the obtained two-dimensional crystal is not in contact with a substrate, thereby reducing defects , to obtain high-quality two-dimensional planar perovskite single crystals. Include the following steps:

(1) Dissolve AX and BX ₂ in the precursor solvent according to a certain proportion to obtain a precursor solution system, and heat and stir to obtain a clear and transparent ABX ₃ solution. Wherein, the concentration of ABX ₃ precursor solution is 0.1 wt% to saturated solution concentration, wherein, A is one or more of MA ⁺ , FA ⁺ , Cs ⁺ , B is Pb ²⁺ , Sn ²⁺ or both, X is one or more of Cl ⁻ , Br ⁻ , I ⁻ , and .

(2) Take the above ABX ₃ solution, drop it onto a clean flat substrate and spread it out to form a film;

(3) Add the limiting phase solvent dropwise onto the ABX ₃ solution film and cover it completely to form a liquid-liquid interface, limit the thickness of the solution and isolate moisture and air. Wherein, the confinement layer solution and the ABX ₃ solution are immiscible or the solubility is very small, and the density should be less than the density of the ABX ₃ solution;

(4) standing and growing at low temperature for a period of time to obtain a two-dimensional perovskite single crystal.

A method for preparing a two-dimensional perovskite single crystal is characterized in that the volume of the dropwise precursor solution and the size of the substrate can be adjusted according to the required crystal thickness, and the obtained crystal thickness is between 100 nm and 5 mm.

A method for preparing a two-dimensional perovskite single crystal, characterized in that the precursor solvent is one of dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, and γ-butyrolactone. species or their mixtures.

A method for preparing a two-dimensional perovskite single crystal, characterized in that the plane substrate can be glass, silicon wafer, polyethylene terephthalate, polytetrafluoroethylene or other predictable plane substrates.

A method for preparing a two-dimensional perovskite single crystal, characterized in that the limiting solution is silicone oil or a non-polar solvent of polycarbon alkanes that meets the density condition.

A method for preparing a two-dimensional perovskite single crystal, characterized in that the low temperature range is 0-80° C. and the growth time is 0.1 hour-10 days.

Compared with the common perovskite single crystal with large surface area to volume ratio, the present invention has the following advantages:

(1) Using the liquid-liquid phase confinement method to grow single crystals, the growth of single crystals in the thickness direction can be inhibited by the thickness of the precursor solvent layer itself, and the liquid level in the thickness direction is limited without affecting the crystals in other directions. growth, the obtained single crystal has a small thickness and a large area;

(2) The contact between the perovskite single crystal and the substrate is reduced by the liquid-liquid interface confinement, thereby reducing the defects of the single crystal;

(3) The precursor liquid can diffuse into the confinement solution and volatilize slowly, increasing the concentration of the precursor liquid and promoting the growth. Compared with the inversion growth method, the required temperature is lower and the growth is slow, which ensures the crystal quality;

(4) The growth process is simple, easy to operate, and the growth cycle is short, which has great application value in the growth of perovskite single crystals;

(5) The prepared single crystal has a maximum size of 8 mm and a thickness of only 50 µm, which has the advantages of large size and small thickness compared with the current reports.

Description of drawings

Fig. 1 is the growth roadmap of perovskite single crystal;

Figure 2 is a 3D confocal micrograph of a MAPbCl ₃ perovskite single crystal on a substrate and its cross-sectional thickness map;

Figure 3 is the XRD pattern of the MAPbCl ₃ perovskite single crystal.

Detailed ways

In order to make the substantive features of the present invention and its practicability easier to understand, the technical solutions of the present invention are further described in detail below with reference to the accompanying drawings and some specific embodiments. However, the following descriptions and explanations about the embodiments do not constitute any limitation to the protection scope of the present invention, and the functions, methods, or equivalent transformations or substitutions made by those of ordinary skill in the art according to these embodiments all belong to the protection scope of the present invention. within:

Example 1

Experimental procedure for MAPbBr3 _perovskite single crystal:

(1) Dissolve lead bromide and ammonium bromide salt in dimethylformamide, heat and stir to dissolve to form a clear and transparent MAPbBr ₃ precursor solution, the molar ratio of the lead bromide and ammonium bromide salt is 1:1, and the mass fraction of the MAPbBr ₃ precursor solution is 30%;

(2) Place the above MAPbBr ₃ precursor solution at a constant temperature for 6-12 h, filter the precursor solution with a 0.22 μm nylon filter head, put the filtered solution into a sample bottle, and seal it for later use;

(3) Ultrasonic cleaning of the glass plate base with detergent, deionized water, acetone, and isopropanol, respectively, and drying for use;

(4) Take the above filtered MAPbBr ₃ solution, use a pipette to measure an appropriate amount of the solution, drop the solution onto the glass plate and spread it out naturally to form a film, as shown in Figure 1;

(5) Add 1 ml of silicone oil dropwise to the top of the MAPbBr ₃ solution film with a dropper and cover it completely, limiting the thickness of the solution and isolating moisture and air. After standing in an incubator for several hours, grow on a glass plate Ultrathin planar perovskite single crystal seeds were seeded, and larger crystals were obtained after about 1-2 days.

Example 2

Experimental steps for flexible MAPbBr3 _perovskite single crystals:

(1) Dissolve lead bromide and ammonium bromide salt in dimethylformamide, heat and stir to dissolve to form a clear and transparent MAPbBr ₃ precursor solution, the molar ratio of the lead bromide and ammonium bromide salt is 1:1, and the mass fraction of the MAPbBr ₃ precursor solution is 30%;

(2) Place the above MAPbBr ₃ precursor solution at a constant temperature for 6-12 h, filter the solution with a 0.22 μm nylon filter head, put the filtered solution into a sample bottle, and seal it for later use;

(3) Clean and dry the peeled mica substrate for later use;

(4) Take the above filtered MAPbBr ₃ solution, measure an appropriate amount of the solution with a pipette, drop the solution onto the mica and spread it out to form a film naturally;

(5) Add 1 ml of silicone oil dropwise to the top of the MAPbBr ₃ solution film with a dropper and cover it completely, limiting the thickness of the solution and isolating moisture and air, and after standing in an incubator for several hours, grow on mica Ultrathin planar perovskite single crystal seeds were obtained after about 1-2 days to obtain larger, somewhat flexible crystals.

Example 3

Experimental procedure for MAPbCl3 _perovskite single crystal:

(1) Dissolve lead chloride and ammonium chloride salt in dimethyl sulfoxide, heat and stir to dissolve to form a clear and transparent MAPbCl ₃ precursor solution, the molar ratio of the lead chloride and ammonium chloride salt is 1:1, and the mass fraction of MAPbCl ₃ precursor solution is 30%;

(2) Place the above MAPbCl ₃ precursor solution at a constant temperature for 6-12 h, filter the solution with a 0.22 μm nylon filter head, put the filtered solution into a sample bottle, and seal it for later use;

(3) Clean the glass plate base with detergent, deionized water, acetone, and isopropanol by ultrasonic cleaning and blow dry for use;

(4) Take the above filtered MAPbCl ₃ precursor solution, measure an appropriate amount of the solution with a pipette, drop the solution onto the glass plate and spread it out to form a film naturally;

(5) Add 1 mL of silicone oil dropwise to the top of the MAPbCl ₃ solution film with a dropper and cover it completely to limit the thickness of the solution and isolate moisture and air. After standing in an incubator for about 1 day, grow on a glass plate Ultrathin planar perovskite single crystal seeds were seeded, and after about 3-4 days, larger crystals were obtained, as shown in Figure 2, the crystal size could reach 2 mm, and its thickness was only 40 µm. Figure 3 is the XRD pattern of perovskite single crystal, the diffraction peaks are 15.57°, 31.43°, 47.95°, 65.62°, corresponding to (100), (200), (300) and (400) of the cubic crystal structure, respectively Planes. Its full width at half maximum (FWHM) is 0.049°, 0.058°, 0.067° and 0.085°, which are in the leading position in literature reports, indicating that the crystal has high quality.

Example 4

Experimental procedure for MAPbI ₃ perovskite single crystal:

(1) Dissolve lead iodide and ammonium iodide salt in γ-butyrolactone, heat and stir to dissolve, so as to form a clear and transparent MAPbI ₃ precursor solution, the molar ratio of the lead iodide and ammonium iodide salt is 1:1, and the mass fraction of the MAPbI ₃ precursor solution is 30%;

(2) Place the above MAPbI ₃ precursor solution at a constant temperature for 6-12 h, filter the solution with a 0.22 μm nylon filter head, put the filtered solution into a sample bottle, and seal it for later use;

(3) Clean the glass plate base with detergent, deionized water, acetone, and isopropanol by ultrasonic cleaning and blow dry for use;

(4) Take the above filtered MAPbI ₃ solution, measure an appropriate amount of the solution with a pipette, drop the solution onto the glass plate and spread it out to form a film naturally;

(5) Add 1 mL of silicone oil dropwise to the top of the MAPbI ₃ solution film with a dropper, and cover it completely to limit the thickness of the solution and isolate moisture and air. After standing in an incubator for about 1 day, grow on a glass plate Ultrathin planar perovskite single crystal seeds were seeded, and larger crystals were obtained after about 3-4 days.

Example 5

Experimental procedure for CsPbBr3 _perovskite single crystal:

(1) Dissolving lead bromide and cesium bromide in dimethyl sulfoxide, heating and stirring to dissolve, to form a clear and transparent CsPbBr ₃ precursor solution, the molar ratio of the lead bromide and cesium bromide is 1 : 1, the mass fraction of CsPbBr ₃ precursor solution is 30%;

(2) Put the above CsPbBr ₃ solution at a constant temperature for a period of time, filter the solution with a 0.22 μm nylon filter head, put the filtered solution into a sample bottle, and seal it for later use;

(3) Ultrasonic cleaning of the glass plate base with detergent, deionized water, acetone, and isopropanol, respectively, and drying for use;

(4) Take the above filtered CsPbBr ₃ solution, use a pipette to measure an appropriate amount of the solution, drop the solution onto the glass plate and spread it out to form a film naturally;

(5) Add silicone oil dropwise to the top of the CsPbBr ₃ solution film with a dropper, and cover it completely to limit the thickness of the solution and isolate moisture and air. Thin planar perovskite single crystal seeds, after about 5 days, yielded larger crystals.

Example 6

Experimental procedure for CsPbCl3 _perovskite single crystal:

(1) Dissolve lead chloride and cesium chloride in dimethyl sulfoxide, heat and stir to dissolve to form a clear and transparent CsPbCl ₃ precursor solution, and the molar ratio of lead bromide and cesium bromide is 1 : 1, the mass fraction of CsPbCl ₃ precursor solution is 30%;

(2) The above CsPbCl ₃ solution was kept at a constant temperature for a period of time, the solution was filtered with a 0.22 μm nylon filter head, and the filtered solution was placed in a sample bottle and sealed for later use;

(3) Ultrasonic cleaning of the glass plate base with detergent, deionized water, acetone, and isopropanol, respectively, and drying for use;

(4) Take the above filtered CsPbCl ₃ solution, use a pipette to measure an appropriate amount of the solution, drop the solution onto the glass plate and spread it out naturally to form a film;

(5) Add silicone oil dropwise to the top of the CsPbCl ₃ solution film with a dropper, and cover it completely to limit the thickness of the solution and isolate moisture and air. Thin planar perovskite single crystal seeds, after about 5 days, yielded larger crystals.

Claims (5)

1. A preparation method of a two-dimensional perovskite single crystal is characterized in that the two-dimensional perovskite single crystal is prepared by a liquid-liquid phase confinement method, the upper surface of the obtained two-dimensional perovskite single crystal is not contacted with a substrate, so that defects are reduced, and the high-quality two-dimensional perovskite single crystal is obtained, and the preparation method comprises the following steps:

(1) mixing AX and BX ₂ Dissolving in precursor solvent according to a certain proportion to obtain precursor solution system, heating and stirring to obtain clear and transparent ABX ₃ Precursor solution of ABX ₃ The concentration of the precursor solution is 0.1 wt% to the concentration of a saturated solution, wherein A is MA ⁺ 、FA ⁺ 、Cs ⁺ B is Pb ²⁺ 、Sn ²⁺ One or two of them, X is Cl ⁻ 、Br ⁻ 、I ⁻ One or more of;

(2) taking the above ABX ₃ Dripping the precursor solution on a clean plane substrate and spreading the precursor solution to form a film;

(3) dropping limiting phase solvent to ABX ₃ Covering the precursor solution film completely to form a liquid-liquid interface, and isolating water and air by limiting the thickness of the phase solvent, wherein the phase solvent and ABX are limited ₃ The precursor solution is immiscible and has a density less than ABX ₃ Density of the precursor solution;

(4) standing at low temperature for a period of time to obtain a two-dimensional perovskite single crystal;

the limiting phase solvent is silicone oil.

2. The method for producing a two-dimensional perovskite single crystal as claimed in claim 1, wherein ABX is added dropwise in an adjustable manner according to a desired thickness of the two-dimensional perovskite single crystal ₃ The volume of the precursor solution and the size of the substrate, and the thickness of the obtained two-dimensional perovskite single crystal is between 100 nm and 5 mm.

3. The method for preparing a two-dimensional perovskite single crystal as claimed in claim 1, wherein the precursor solvent is one of dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, gamma-butyrolactone or a mixture thereof.

4. The method for preparing a two-dimensional perovskite single crystal as claimed in claim 1, wherein the planar substrate is a glass or silicon wafer or polyethylene terephthalate or polytetrafluoroethylene.

5. The process for producing a two-dimensional perovskite single crystal as claimed in claim 1, wherein said low temperature is in the range of 0 to 80 ℃ and the growth time is in the range of 0.1 hour to 10 days.

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