A chiral perovskite crystal sheet and its preparation method and application

Abstract

The present invention relates to a chiral perovskite crystal sheet and its preparation method and application, belonging to the field of optoelectronic materials and device technology. The preparation method of the chiral perovskite crystal sheet is: first the chiral organic ligand (R / S)-methylbenzylamine with a helical structure is co-placed in a closed environment with a perovskite precursor solution prepared by PbO and HBr to react, and then successively heated by an oil bath, naturally cooled, vacuum filtered, washed and dried. Compared with conventional preparation methods, the method is simple, time-consuming, and the efficiency and yield of preparing single crystals are high, and there are no strict requirements on the order of adding chemical reagents, material ratios, and operating environments. The prepared single crystal is large in size (about 1 cm in length), high in hardness, thick in sheet shape, and has the characteristics of being not easily broken, while showing good circular dichroism and chiral induced spin selection characteristics, so as to have a huge application prospect in chiral spin optoelectronic devices.

Description

Technical Field

[0001] The invention belongs to the technical field of optoelectronic materials and devices, and relates to a chiral perovskite crystal sheet and a preparation method and application thereof. Background Art

[0002] Organic-inorganic hybrid perovskite semiconductor materials have great application prospects in the fields of solar cells, light-emitting diodes, lasers, transistors and other optoelectronics due to their excellent photophysical and photochemical properties. The chemical formula of conventional organic-inorganic hybrid perovskite semiconductor materials can be expressed as ABX3 (where A represents organic cations, B represents divalent metal cations, and X represents halogen anions). By changing the chemical components of A, B and X, the optical, electrical, magnetic and other physical properties of perovskite semiconductor materials can be effectively regulated. For example, when the non-chiral organic cation at position A is replaced with a chiral organic cation, the replacement process will not destroy the original crystal structure of the perovskite, but will affect its photophysical properties, and can give the perovskite material natural optical activity such as circular dichroism and circularly polarized luminescence characteristics. Perovskites with such optical properties are also called chiral perovskites, which can be widely used in nonlinear optical fields such as circularly polarized luminescence, detection or lasers.

[0003] In addition to the above-mentioned natural optical activity, studies have shown that chiral perovskites also have intrinsic spin electronics properties. On the one hand, due to the presence of heavy metal elements Pb in chiral perovskites, a strong spin-orbit coupling physical effect will be generated inside the material; on the other hand, due to the chiral properties of chiral perovskites, the material produces chiral-induced spin-orbit coupling, which causes the electron spin energy level to change from a degenerate state to a non-degenerate state, thereby generating left-handed or right-handed circularly polarized light. Based on this chiral spin-light physical property, when spin-polarized electrons are transported in chiral perovskites, the material can well screen the spin states of electrons with spins up or down, that is, chiral perovskites have chiral-induced spin selection properties. This property can achieve effective regulation of spin quantum states, making chiral perovskites promising for use in spin electronics devices such as spin electron injection, transport, and detection.

[0004] At present, there are two main methods for preparing chiral perovskite crystals, namely direct method and indirect method. The direct method is to first prepare a lead halide inorganic perovskite precursor solution in a vacuum or nitrogen atmosphere, then add a chiral organic ligand to allow chemical bond hybridization between the chiral organic cation and the inorganic perovskite skeleton to form a solid-liquid mixture, and then heat the mixture until the solid disappears completely. After cooling, standing, washing and drying, irregular chiral perovskite crystals such as needle-shaped or block-shaped are obtained; the indirect method includes anti-solvent vapor-assisted crystallization and self-assembled chiral organic ligand exchange. The experimental technical scheme of the anti-solvent vapor-assisted crystallization method is to first add chloroform to the prepared inorganic perovskite precursor solution, wait for the chloroform to slowly penetrate into the surface of the inorganic perovskite, and obtain an intermediate of the inorganic perovskite and the organic solvent; then add the chiral organic ligand to the anti-solvent of the perovskite to obtain the anti-solvent solution of the chiral organic ligand; finally, place the intermediate and the anti-solvent solution together in a closed system, and form chiral perovskite crystals by slowly evaporating the chiral organic ligand into the intermediate. The experimental technical scheme of the self-assembled chiral organic ligand exchange method is to place the prepared colloidal inorganic perovskite nanocrystals under microwave irradiation for a certain time and temperature, with the inorganic perovskite as the non-chiral center and the chiral organic ligand as the inclusion, and obtain chiral perovskite crystals by encapsulating the inorganic perovskite with the chiral organic ligand.

[0005] However, both the direct method and the indirect method have certain shortcomings: (1) The direct method requires strict adherence to the experimental sequence, the heating temperature needs to be strictly controlled, and the entire preparation process requires the protection of inert gas; (2) The product of the antisolvent vapor-assisted crystallization method is easily affected by multiple factors such as the antisolvent vapor evaporation time and rate, ambient temperature, etc. The experimental operation steps are many, the experimental environment is demanding, and the crystallization time is difficult to control; the self-assembled chiral organic ligand exchange method requires the advance preparation of inorganic perovskite nanocrystals, and the microwave irradiation temperature and time need to be set in advance. The product has weak chirality, which is not conducive to obtaining low-dimensional chiral perovskite crystals. More importantly, if the preparation conditions change slightly during the experiment, the number, crystallinity and chiral properties of the chiral perovskite crystals are easily affected.

[0006] Looking at the existing technologies, the preparation methods of chiral perovskite single crystals are relatively complicated, the crystal morphology is difficult to control, and the prepared products generally show characteristics such as needle-like shape, small size, easy to break, and weak intrinsic chirality, which greatly restricts its practical application in spintronic devices. Therefore, it is necessary to propose a preparation method of chiral perovskite crystals that is simple and easy to operate, has a high crystal success rate and output rate, is easy to control the crystal morphology, and is suitable for preparing spintronic devices. Summary of the invention

[0007] In view of this, one of the objects of the present invention is to provide a method for preparing a chiral perovskite crystal sheet; a second object of the present invention is to provide a chiral perovskite crystal sheet; a third object of the present invention is to provide an application of a chiral perovskite crystal sheet in the preparation of a spin valve device or a spin-circular photovoltaic effect device.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] 1. A method for preparing a chiral perovskite crystal sheet, the preparation method being as follows:

[0010] (1) completely dissolving lead monoxide in hydrobromic acid to obtain a perovskite precursor solution, then placing the perovskite precursor solution and a chiral organic ligand having a helical structure in a sealed container, heating and stirring at 50° C. for 3 h, and then continuing to stir at room temperature for 3 h to obtain a solid-liquid mixture;

[0011] The chiral organic ligand having a helical structure is any one of (R)-(+)-α-methylbenzylamine or (S)-(-)-α-methylbenzylamine;

[0012] (2) placing the solid-liquid mixture in step (1) in an oil bath, heating at 80° C. for 50 min to obtain a colorless transparent solution, and naturally cooling the colorless transparent solution to room temperature under a static state, and then vacuum filtering, washing with toluene, and drying to obtain a chiral perovskite crystal sheet.

[0013] Preferably, the molar ratio of lead monoxide to hydrobromic acid in step (1) is 1:1.

[0014] Preferably, the volume ratio of the chiral organic ligand having a helical structure to the perovskite precursor solution in step (1) is 1:3.

[0015] Preferably, the specific process of drying in step (2) is: first vacuumizing and then heating to dry.

[0016] Preferably, the vacuuming time is 10 minutes; the heating and drying temperature is 100° C. and the time is 12 hours.

[0017] 2. The chiral perovskite crystal sheet prepared by the preparation method.

[0018] 3. Application of the chiral perovskite crystal sheet in the preparation of spin valve devices or spin circular photovoltaic effect devices.

[0019] The beneficial effect of the present invention is that the present invention provides a method for preparing a chiral perovskite crystal sheet. In the preparation process, PbO, HBr and a chiral organic ligand (R / S)-methylbenzylamine with a helical structure are used as reaction raw materials. A perovskite precursor solution is prepared by PbO and HBr, and the precursor solution and the chiral organic ligand are placed in a closed environment, first heated and stirred, and then stirred at room temperature to obtain a solid-liquid mixture, and the solid-liquid mixture is heated in an oil bath, cooled, vacuum filtered, washed and dried to obtain a chiral perovskite crystal sheet. The method for forming the solid-liquid mixture is a chiral organic ligand steam-assisted crystallization method. First, this method does not need to strictly calculate the content of chiral organic ligands. It only needs to wait for the formation of precipitates in the perovskite precursor solution. When the precipitate is completely formed, the evaporation is quickly stopped, which can effectively prevent the loss of chemical reagents; second, the chiral organic molecules can be more efficiently hybridized with the inorganic perovskite; third, by selecting a suitable temperature (50°C), the evaporation rate is effectively adjusted, thereby regulating the formation rate and amount of chiral perovskite precipitation, and producing a chiral perovskite with a different crystal structure and crystallinity from the prior art (the single crystals prepared by the prior art are generally needle-shaped, and the single crystals prepared in this application are sheet-shaped), realizing the regulation of the dimensions and chiral optical properties of the chiral perovskite. In short, compared with conventional preparation methods, the preparation method in this application is simple, highly operable, has a high single crystal success rate and yield, is time-consuming, does not require strict adherence to the experimental sequence and the chemical ratio of the raw materials, and is expected to achieve industrial production of chiral perovskite crystal sheets. Compared with the preparation method of lead iodine perovskite crystals with the same type of chiral organic ligands, this preparation method can more effectively regulate the circularly polarized luminescence and spin electronics properties of chiral perovskites.

[0020] The present invention also provides a chiral perovskite crystal sheet ((R / S-MBA)2PbBr4). The chiral perovskite crystal sheet prepared by the method of the present application has strong chiral characteristics, and compared with the chiral lead iodine perovskite crystal of the same type of chiral organic ligand, it has stronger circular dichroism. Its circular dichroism spectrum only shows two obvious circular dichroism signal peaks, without other interference signals, indicating that the chiral perovskite crystal sheet has strong chiral induced spin selection characteristics. More importantly, the prepared chiral perovskite is a large-sized, high-hardness, thick single crystal, which is not easy to break, and is extremely suitable for preparing spin-valve-like devices or spin-circular photovoltaic effect devices, realizing effective manipulation of quantum information such as spin states.

[0021] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0023] Figure 1 The morphology of crystals precipitated from the colorless transparent solution obtained in step (2) of Example 1 and Example 2 during natural cooling under a static state, wherein a is the morphology of crystals precipitated from the colorless transparent solution obtained in step (2) of Example 1 during natural cooling under a static state, and b is the morphology of crystals precipitated from the colorless transparent solution obtained in step (2) of Example 2 during natural cooling under a static state;

[0024] Figure 2 ] are appearance morphology pictures of the chiral perovskite crystal sheets ((R / S-MBA)2PbBr4) prepared in Examples 1 and 2, wherein a is an appearance morphology picture of the chiral perovskite crystal sheet ((R-MBA)2PbBr4) with a right-handed configuration prepared in Example 1, and b is an appearance morphology picture of the chiral perovskite crystal sheet ((S-MBA)2PbBr4) with a left-handed configuration prepared in Example 2;

[0025] Figure 3 The morphology of the chiral perovskite crystal sheet with a right-handed configuration ((R-MBA)2PbBr4) prepared in Example 1 and the chiral perovskite crystal sheet with a left-handed configuration ((S-MBA)2PbBr4) prepared in Example 2 under a microscope;

[0026] Figure 4 Circular dichroism spectra of the chiral perovskite crystal sheet with right-handed configuration ((R-MBA)2PbBr4) prepared in Example 1 and the chiral perovskite crystal sheet with left-handed configuration ((S-MBA)2PbBr4) prepared in Example 2;

[0027] Figure 5 The normalized optical absorption spectra of the chiral perovskite crystal sheet with right-handed configuration ((R-MBA)2PbBr4) prepared in Example 1 and the chiral perovskite crystal sheet with left-handed configuration ((S-MBA)2PbBr4) prepared in Example 2 in the visible light range;

[0028] Figure 6 The normalized X-ray powder diffraction patterns of the chiral perovskite crystal sheet with a right-handed configuration ((R-MBA)2PbBr4) prepared in Example 1 and the chiral perovskite crystal sheet with a left-handed configuration ((S-MBA)2PbBr4) prepared in Example 2;

[0029] Figure 7Schematic diagram of the application of the chiral perovskite crystal sheets ((R / S-MBA)2PbBr4) prepared in Example 1 and Example 2 in spin valve devices and spin circular photovoltaic effect devices, wherein a is a schematic diagram of the application in the spin valve device and b is a schematic diagram of the application in the spin circular photovoltaic effect device. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0031] Example 1

[0032] A chiral perovskite crystal sheet with a right-handed configuration ((R-MBA)2PbBr4), the preparation method of which is as follows:

[0033] (1) Weigh 400 mg of yellow lead monoxide powder at room temperature and then put it into a 20 mL clean and transparent glass bottle. Add 6 mL of hydrobromic acid to the glass bottle. After the yellow powder is completely dissolved in the hydrobromic acid, a yellow perovskite precursor solution is obtained. Take 6 mL of the precursor solution and place it and 2 mL of a helical chiral organic ligand (R)-(+)-α-methylbenzylamine (R-MBA) in a sealed container. Then place the sealed container on a hot plate at 50° C. Turn on the heating and stirring function of the hot plate to allow the chiral organic ligand to evaporate continuously to generate steam. After heating and stirring for 3 hours, in order to ensure that the steam is fully dissolved in the perovskite precursor solution, a stirring magnet is added to the precursor solution. Then, stirring is continued for 3 hours at room temperature to obtain a white solid-liquid mixture.

[0034] (2) The white solid-liquid mixture in step (1) is placed in an oil bath at 80° C. and heated for 50 min to obtain a colorless transparent solution. The colorless transparent solution is naturally cooled to room temperature in a static state, and then quickly poured into a vacuum filter, and washed repeatedly with toluene for 3 times to rinse off the residual solvent on the crystal surface and the overlapping connection positions of the crystals. The crudely extracted crystals are placed in a vacuum chamber and evacuated for 10 min, and then placed in an oven at 100° C. and dried for 12 h. The residual solvent on the crystal surface is evaporated again to obtain a chiral perovskite crystal sheet with a right-handed configuration.

[0035] Example 2

[0036] A chiral perovskite crystal sheet ((S-MBA)2PbBr4) with a left-handed configuration, the preparation method of which is as follows:

[0037] The difference from Example 1 is that the chiral organic ligand (R)-(+)-α-methylbenzylamine (R-MBA) with a helical structure in step (1) is replaced by a chiral organic ligand (S)-(-)-α-methylbenzylamine (S-MBA) with a helical structure.

[0038] The chemical reagents required for preparing the chiral perovskite crystal sheet ((R / S-MBA)2PbBr4) in the above-mentioned Example 1 and Example 2 are all commercially available. The properties, purity, brand and proportion of each chemical reagent are shown in Table 1 below:

[0039] Table 1 Experimental reagents, properties, purity, brand and proportion

[0040]

[0041] Figure 1 The morphology of the crystals precipitated from the colorless transparent solution obtained in step (2) of Example 1 and Example 2 during natural cooling under a static state, wherein a is the morphology of the crystals precipitated from the colorless transparent solution obtained in step (2) of Example 1 during natural cooling under a static state, and b is the morphology of the crystals precipitated from the colorless transparent solution obtained in step (2) of Example 2 during natural cooling under a static state. Figure 1 It can be seen from a and b that the precipitated crystals are all white and have the same morphology, appearing in the form of flakes.

[0042] Figure 2 The appearance morphology of the chiral perovskite crystal sheet ((R / S-MBA)2PbBr4) prepared in Example 1 and Example 2, wherein a is the appearance morphology of the chiral perovskite crystal sheet ((R-MBA)2PbBr4) with a right-handed configuration prepared in Example 1, and b is the appearance morphology of the chiral perovskite crystal sheet ((S-MBA)2PbBr4) with a left-handed configuration prepared in Example 2. Figure 2 As can be seen from a and b, the two prepared crystals are white and large in size, with a crystal length of about 1 cm.

[0043] In order to more clearly observe the microscopic morphology of the chiral perovskite crystal sheet (R-MBA)2PbBr4 with a right-handed configuration prepared in Example 1 and the chiral perovskite crystal sheet (S-MBA)2PbBr4 with a left-handed configuration prepared in Example 2, we placed the crystal samples under an optical microscope and observed the surface morphology as follows: Figure 3 As shown. Figure 3It can be observed that the two chiral perovskite crystals prepared both present a sheet-like structure, with the sheets sticking to each other, and each crystal has a thickness. If the crystal sheets are peeled off from each other, the crystal sheets can be used to prepare chiral spin optoelectronic devices such as spin valves and spin photovoltaics. Spin optoelectronic devices can better study the transport process of spin-polarized electrons inside chiral perovskite materials, thereby realizing the effective manipulation of spin quantum information and spin states and improving quantum information transmission technology.

[0044] In order to characterize the chiral properties of the chiral perovskite crystal sheets prepared in Example 1 and Example 2, we tested the circular dichroism spectra of (R-MBA)2PbBr4 and (S-MBA)2PbBr4 crystal sheets, such as Figure 4 As shown. Figure 4 It can be seen that the circular dichroism curves of these two chiral perovskites have obvious symmetry, and two strong circular dichroism signals appear at 318nm and 335nm respectively. This shows that the chiral perovskite crystal sheets (R-MBA)2PbBr4 and (S-MBA)2PbBr4 prepared by the method in this application have strong chirality, and also verifies that the chiral organic ligand can efficiently transfer chirality to the inorganic perovskite structure, and through the hybridization and interaction of the electron orbits between the organic and inorganic components, the overall chiral perovskite produces chiral optical functions.

[0045] Figure 5 The optical absorption characteristics of the chiral perovskite crystal sheet (R-MBA) 2PbBr4 with a right-handed configuration prepared in Example 1 and the chiral perovskite crystal sheet (S-MBA) 2PbBr4 with a left-handed configuration prepared in Example 2 in the visible light range are shown. In order to clearly compare the photophysical properties of the two, the absorption spectra are normalized. Figure 5 It can be seen that the light absorption band edge of (R-MBA)2PbBr4 is located at 343nm, and the light absorption band edge of (S-MBA)2PbBr4 is located at 335nm. It can be seen that the exciton binding energy of the two is relatively close, and they have similar photophysical properties. This shows that the chiral perovskite crystal sheet (R-MBA)2PbBr4 and (S-MBA)2PbBr4 have the same circularly polarized luminescence characteristics.

[0046] Figure 6 The crystallization characteristics of the chiral perovskite crystal sheet (R-MBA) 2PbBr4 with a right-handed configuration prepared in Example 1 and the chiral perovskite crystal sheet (S-MBA) 2PbBr4 with a left-handed configuration prepared in Example 2 are shown. Figure 6It can be seen that both chiral perovskite crystal sheets will produce two obvious crystallization peaks, located at approximately 8° and 16°, that is, the crystal orientation grows along the (002I) (where I = 1, 2, 3,,,) plane. The experimental results show that (R-MBA)2PbBr4 and (S-MBA)2PbBr4 present similar crystal orientation and crystallinity, and both of them have high crystallization properties.

[0047] If the crystal sheets are peeled off from each other, the chiral perovskite crystal sheets ((R / S-MBA)2PbBr4) prepared in Example 1 and Example 2 can be used to prepare chiral spin optoelectronic devices. Spin electronic devices can better study the spin polarized electron transport process inside chiral perovskite materials, thereby realizing the effective manipulation of spin quantum information and spin states. Figure 7 The application of chiral perovskite crystal sheets (R / S-MBA) 2PbBr4 in the preparation of spin valve devices and spin photovoltaic effect devices was demonstrated. Figure 7 a is a schematic diagram of the application in spin valve devices. Figure 7 Figure b is a schematic diagram of its application in a spin-valve photovoltaic effect device. In the spin valve device, from bottom to top, there are non-ferromagnetic electrodes, chiral perovskite crystal sheets (R / S-MBA)2PbBr4, and ferromagnetic electrodes (top electrodes). Its working principle is that by injecting free electrons from the non-ferromagnetic bottom electrode, based on the strong chiral induced spin selection and chiral induced spin-orbit coupling properties of the chiral perovskite crystal sheet, spin-polarized electrons with spin-up or spin-down orientation in the chiral perovskite crystal sheet can be well screened out, and then enter the ferromagnetic top electrode through the spin transport process. Obviously, as long as the spin-polarized electron state orientation in the chiral perovskite crystal sheet is opposite or the same as the spin state orientation in the ferromagnetic top electrode, the spin valve effect (opposite spin orientation) or magnetoresistance effect (same spin orientation) can be achieved. In the spin-valve photovoltaic effect device, the structural composition is glass substrate / non-magnetic electrode / chiral perovskite crystal sheet (R / S-MBA)2PbBr4 / non-magnetic electrode. Its working principle is that when left-handed or right-handed circularly polarized light is used to illuminate a chiral perovskite single crystal, the non-magnetic electrodes on both sides of the chiral perovskite single crystal can effectively extract free electrons in the chiral perovskite single crystal. Since the distance between the two electrodes is at the micron level, the photogenerated current signal can be detected. At the same time, by rotating the 1 / 4 wave plate and changing the polarization state of the incident light, the circularly polarized light-dependent photocurrent effect can be observed. The device structure belongs to an in-plane lateral optoelectronic device. By studying the relationship between the polarization state of the incident light and the helical structure of the material, it is helpful to deeply understand the chiral induced spin selection characteristics of chiral perovskites, thereby expanding the application prospects of the device.

[0048] In summary, the present invention provides a method for preparing a chiral perovskite single crystal sheet. The preparation method is simple, time-saving, has no strict requirements on experimental steps, raw material ratios, and operating environment, has a high success rate and yield of the prepared single crystal, and can realize industrial and market-oriented preparation.

[0049] The present invention also provides a chiral perovskite single crystal. The single crystal prepared by the method of the present application is a large-sized, high-hardness, thick sheet. Experimental results show that the single crystal has excellent chirality, exhibits strong circular dichroism and crystallinity, and also has strong chiral induced spin selection characteristics, so it is extremely suitable for chiral spin optoelectronic devices.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a chiral perovskite crystal sheet, characterized in that: The preparation method is as follows: (1) completely dissolving lead monoxide in hydrobromic acid to obtain a perovskite precursor solution, then placing the perovskite precursor solution and a chiral organic ligand having a helical structure in a sealed container, heating and stirring at 50° C. for 3 h to allow the chiral organic ligand having a helical structure to continuously evaporate and generate steam, and in order to ensure that the steam is fully dissolved in the perovskite precursor solution, continuing to stir at room temperature for 3 h to obtain a solid-liquid mixture; The chiral organic ligand having a helical structure is any one of (R)-(+)-α-methylbenzylamine or (S)-(-)-α-methylbenzylamine; (2) placing the solid-liquid mixture in step (1) in an oil bath, heating at 80° C. for 50 min to obtain a colorless transparent solution, and naturally cooling the colorless transparent solution to room temperature under a static state, and then vacuum filtering, washing with toluene, and drying to obtain a chiral perovskite crystal sheet.

2. The preparation method according to claim 1, characterized in that: The molar ratio of lead monoxide to hydrobromic acid in step (1) is 1:

1.

3. The preparation method according to claim 1, characterized in that: The volume ratio of the chiral organic ligand with a helical structure to the perovskite precursor solution in step (1) is 1:

3.

4. The preparation method according to claim 1, characterized in that: The specific process of drying in step (2) is: first vacuumizing and then heating and drying.

5. The preparation method according to claim 4, characterized in that: The vacuuming time is 10 minutes; the heating and drying temperature is 100° C. and the time is 12 hours.

6. A chiral perovskite crystal sheet prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the chiral perovskite crystal sheet according to claim 6 in the preparation of a spin valve device or a spin circular photovoltaic effect device.

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