D-J type two-dimensional perovskite LPbI4 single crystal based on organic ligands with different chain lengths as well as preparation method and luminescence regulation and control method of D-J type two-dimensional perovskite LPbI4 single crystal

Abstract

The invention discloses a D-J type two-dimensional perovskite LPbI4 single crystal based on organic ligands with different chain lengths as well as a preparation method and a luminescence regulation and control method of the D-J type two-dimensional perovskite LPbI4 single crystal, and belongs to the technical field of lead halogen perovskite materials. According to the preparation method, solid PbI2 and an organic ligand are subjected to a chemical reaction in an HI solution, the growth process of the two-dimensional perovskite LPbI4 single crystal is controlled by adjusting the raw material ratio, the reaction heating temperature and the annealing temperature and time, and the two-dimensional D-J type perovskite LPbI4 single crystal with n being equal to 1 is finally prepared. According to the invention, double-color emission can be generated without doping, meanwhile, pulse exciting light with different power densities or pulse frequencies can be utilized to excite, regulate and control the light-emitting color, the light-emitting color continuously changes from blue to red along with the increase of the exciting light pulse power or frequency, and the light-emitting color is reversible. The synthesis process has the characteristics of simplicity, environmental protection, small pollution and the like, the crystal quality is high, the single crystal shape is more regular, and the luminescence color regulation and control method is simple and convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of lead halogen perovskite materials, and in particular to a DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths, and a preparation method and a luminescence regulation method thereof. Background Art

[0002] As a new type of "star" semiconductor, organic-inorganic hybrid perovskite has become one of the research hotspots in recent years due to its excellent photophysical properties. Its excellent luminescence efficiency and wavelength tunability make it show broad application prospects in the fields of LED, X-ray scintillator, fluorescence sensor and thermometer. At present, the color and efficiency of perovskite luminescence are mainly regulated by changing the morphology, chemical composition, ion doping and other means. In terms of morphology regulation, it is usually difficult to accurately control the various stages of crystal growth, and the obtained products have problems such as poor crystal quality, poor repeatability, uneven size and poor stability. In terms of chemical composition regulation, although changing the X-position halogen ratio can adjust the band gap and luminescence intensity, the photoinduced phase separation phenomenon limits its application range. In terms of ion doping, metal ion luminescence is a kind of impurity energy level composite luminescence that is different from defect luminescence. It usually presents broadband emission and a long fluorescence lifetime. Commonly used luminescent ions such as: Mn 2+ 、Bi 3+ , Sb 3+ 、Cd 2+ , Cu 2+ 、Te 4+ , rare earth ions, etc. 2+ For example, when electrons are excited by light, they transition to an excited state. Their radiative recombination mainly undergoes two pathways: one is the direct recombination of excited state electrons and holes, and the radiative transition back to the ground state; the other is the excitons passing through Mn 2+ The d→d* radiative transition of Mn is introduced into the emission spectrum. 2+ The orange-red broadband emission of CsPbCl3 has a fluorescence lifetime of μs to ms. However, among all three-dimensional metal halide perovskites, the band gap of CsPbCl3 is most suitable for the free exciton to Mn 2 + The d-state energy level of Mn 2+ The doped CsPbCl3 exhibits narrow band edge emission and broad orange emission.

[0003] Lead halide perovskite materials have excellent photophysical properties, such as long carrier lifetime, long diffusion length and high photoluminescence quantum yield (PLQY), and show great application prospects in the fields of solar cells, light-emitting diodes (LEDs) and other optoelectronic devices. In perovskite semiconductor materials, doping with heteroatoms is a commonly used method to regulate their optical properties. Compared with semiconductors such as CdS or CdSe, the lattice structure of lead halide perovskite has higher "softness" and ion mobility, making it easier for isovalent or heterovalent ions to be doped into the crystal structure of lead halide perovskite. For example, perovskites with mixed halide components can be prepared by simple ion exchange, thereby achieving the regulation of their band gap energy and emission spectrum in the entire visible light region; in addition, the metal cation Pb in lead halide perovskite 2+ It can also be treated by divalent metal cations (such as Sn 2+ , Cu 2+ and Mn 2+ ) partially or completely replaced, Pb 2+ The substitution of Mn not only reduces the use of heavy metals, but also introduces rich optical, magnetic and electrical properties to the host material; 2+ In doped CsPbCl3 nanocrystals (NCs), some of the photogenerated excitons in the perovskite host can be transferred to Mn 2+ On the dopant, Mn 2+ Ions pass through d→d * The transition realizes down-conversion emission, so Mn 2+ The doped perovskite exhibits dual-color emission, including high-energy bandgap emission and low-energy Mn 2+ emission, this characteristic makes Mn 2+ Doped perovskites have become candidate materials for light-emitting sources with tunable emission colors.

[0004] Cadmium-based halide perovskites are also considered to be materials with application potential. 2+ and Pb 2+ They have similar ionic radii and show excellent properties in improving the luminescence performance and stability of lead-based perovskites. For example, Boukheddaden et al. synthesized 1D (C6H 11 NH3)2CdBr4, [CdBr6] 4- The broad peak of the octahedron (2.94 eV) is mixed with the broad peak of the organic component (2.53 eV) to form a single-component white light emitting material; in addition, self-trapped excitons and intrinsic defects can also produce broadband emission. Michael Worku et al. reported broadband emission of one-dimensional C4N2H 14PbBr4 perovskite has a room temperature white light emission PLQYs of 20%, which is attributed to the self-trapped exciton emission generated by the 1D structure. At present, the reported broadband emission perovskite materials have covered the entire visible light spectrum, but the research on efficient luminescent perovskite materials still faces many challenges, so it is crucial to regulate the luminescence performance, explore the luminescence mechanism and understand the relationship between their physical properties.

[0005] Therefore, developing new lead-free halide perovskites, regulating their optical properties such as luminescent color and luminescent efficiency, and studying their luminescence mechanism are of great significance to expanding their application areas. Summary of the invention

[0006] The purpose of the present invention is to provide a DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths, a preparation method thereof, and a luminescence control method. Alkyl diamine ligands of different chain lengths are used to prepare a two-dimensional DJ-type perovskite LPbI4 single crystal with n=1. The preparation method introduces defects, realizes the generation of two-color emission without doping, and the luminescence color can be controlled by changing the excitation light power and frequency. .

[0007] To achieve the above objectives, the present invention provides a luminescence regulation method for a DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands with different chain lengths. The two-dimensional perovskite LPbI4 single crystal utilizes pulsed excitation light with different power densities or pulse frequencies to regulate the luminescence color. The luminescence color changes continuously from blue to red as the excitation light power density or pulse frequency increases; the luminescence color changes continuously from red to blue as the excitation light power density or pulse frequency decreases.

[0008] Preferably, the pulse frequency of the pulsed excitation light is: the excitation light repetition frequency range is 0.01–41 MHz, the laser single pulse energy of different repetition frequencies is consistent, and the laser single pulse energy is 3.5 μJ cm during fluorescence spectrum testing. -2 , the laser single pulse energy in bright field imaging is 7 μJ cm -2 and 10.5 μJ cm -2 .

[0009] Preferably, the power density of the pulsed excitation light is: during fluorescence spectrum testing, the excitation light repetition frequency is 2 MHz, and the variable laser power range is 0.001-10 uw; during bright field imaging, the laser repetition frequency is 5 MHz, and the variable laser power range is 0.001-20 uw; it is divided into wide field and fixed point excitation, and the excitation wavelength is 405 nm.

[0010] The present invention also provides a two-dimensional perovskite LPbI4 single crystal whose luminescent color is regulated by the above-mentioned luminescent regulation method, wherein the two-dimensional perovskite LPbI4 single crystal is a two-dimensional DJ-type perovskite single crystal.

[0011] The preparation method of the DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths is as follows: the two-dimensional perovskite LPbI4 single crystal is finally prepared by an ion exchange reaction between solid PbI2 and organic ligands in HI solution, and the growth process of the two-dimensional perovskite LPbI4 single crystal is controlled by adjusting the proportion of ions in the solution, the reaction heating temperature, and the annealing temperature and time. The basic principle of its synthesis is:

[0012] PbI2(s)+L(s)+2I - →LPbI4(s)

[0013] Preferably, the organic ligand is an alkyl diamine, and the morphology of the two-dimensional perovskite LPbI4 single crystal is regular and geometrical, and the geometrical shape of the two-dimensional perovskite LPbI4 single crystal is related to the chain length of the alkyl diamine.

[0014] Preferably, the specific preparation comprises the following steps:

[0015] (1) Mix solid PbI2 and organic ligands in a reaction bottle, add small amounts of hydroiodic acid to the reaction bottle several times, and heat and stir until the solid reactants are completely dissolved;

[0016] (2) gradually and uniformly cooling the solution in step (1) until the concentration reaches a saturated state and perovskite solid is precipitated to obtain a mother solution;

[0017] (3) Place the coverslip that has been cleaned by ethanol ultrasonication and plasma cleaning on a heating table, use a cotton swab to take a small amount of the mother solution in step (2), apply it on the coverslip for annealing, and let it stand for 5-30 seconds until it is completely dry to obtain a two-dimensional perovskite LPbI4 single crystal with regular morphology.

[0018] Preferably, in step (1), the molar ratio of solid PbI2 to organic ligand is (0.5-4):1.

[0019] Preferably, the heating and stirring temperature in step (1) is 80-180°C.

[0020] Preferably, the coverslip annealing temperature in step (3) is 50-120°C.

[0021] Therefore, the present invention adopts the above-mentioned DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths and its preparation method and luminescence regulation method, which has the following beneficial effects:

[0022] (1) The two-dimensional DJ-type perovskite LPbI4 single crystal material based on alkyl diamines of different chain lengths as organic ligands described in the present invention adopts a simple one-step method to synthesize a saturated solution and a method of rapidly annealing to precipitate single crystals. The synthesis process has the characteristics of simplicity, environmental protection, and low pollution. It can quickly, economically, and greenly synthesize two-dimensional perovskite LPbI4 single crystals with alkyl diamines of different chain lengths as organic ligands. The micron-sized DJ-type two-dimensional perovskite LPbI4 single crystals synthesized by this method have high crystal quality and more regular single crystal shapes.

[0023] (2) The present invention prepares two-dimensional DJ-type perovskite LPbI4 single crystals with different n=1 by changing the chain length of the organic ligand in the two-dimensional perovskite; introduces defects by a synthesis method of rapidly annealing a saturated solution on a cover glass to precipitate a single crystal, thereby achieving perovskite dual-color emission; and can effectively control the luminescent color of the micron-sized DJ-type two-dimensional perovskite LPbI4 single crystal by simply changing the excitation light pulse power and frequency, which is beneficial to its design and application in photovoltaic devices. The present invention has the advantages of simple operation, low equipment requirements, no need for various expensive reaction devices, and easy mass synthesis, and is expected to produce good social and economic effects.

[0024] (3) Different from the more common RP-type two-dimensional perovskite L2PbI4 single crystal supported by van der Waals forces, the two-dimensional perovskite LPbI4 single crystal prepared by the present invention is DJ-type. The organic ligand as a bifunctional divalent cation makes the DJ-type two-dimensional perovskite LPbI4 single crystal in the present invention have a more stable structure. In addition, the current research on the photophysical properties and carrier dynamics characteristics of DJ-type two-dimensional perovskites is not in-depth. In the past, most synthetic samples were powdered single crystals or polycrystalline films, which inevitably affected the grain size and grain boundaries. The LPbI4 single crystal prepared by the present invention has a very regular shape and excellent single crystal quality, and is a good carrier for studying the intrinsic photophysical properties of DJ-type two-dimensional perovskites.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a microscope morphology image of the two-dimensional perovskite LPbI4 single crystal in Example 1;

[0027] Figure 2 This is a microscope morphology image of the two-dimensional perovskite LPbI4 single crystal in Example 2;

[0028] Figure 3 is a SEM image of the two-dimensional perovskite LPbI4 single crystal in Example 1;

[0029] Figure 4 is a SEM image of the two-dimensional perovskite LPbI4 single crystal in Example 2;

[0030] Figure 5 The UV-visible absorption spectrum and steady-state fluorescence spectrum of the two-dimensional perovskite LPbI4 single crystal in Example 1;

[0031] Figure 6 The UV-visible absorption spectrum and steady-state fluorescence spectrum of the two-dimensional perovskite LPbI4 single crystal in Example 2;

[0032] Figure 7 is the power-dependent normalized fluorescence emission spectrum of the two-dimensional perovskite LPbI4 single crystal in Example 3;

[0033] Figure 8 is the power-dependent normalized fluorescence emission spectrum of the two-dimensional perovskite LPbI4 single crystal in Example 4;

[0034] Fig. 9 is the two-dimensional perovskite LPb in Example 5 I4 Frequency-dependent normalized fluorescence emission spectra of single crystals;

[0035] Fig.10 is the frequency-dependent normalized fluorescence emission spectrum of the two-dimensional perovskite LPbI4 single crystal in Example 6;

[0036] Fig.11 This is a photograph of the change in luminescent color of the two-dimensional perovskite LPbI4 single crystal in Example 3 after changing the excitation light power density;

[0037] Fig.12 This is a photograph of the change in luminescent color of the two-dimensional perovskite LPbI4 single crystal in Example 4 after changing the excitation light power density;

[0038] Fig.13 This is a photo of the change in the luminescent color of the two-dimensional perovskite LPbI4 single crystal after changing the laser pulse frequency in Example 5;

[0039] Fig.14 This is a photograph of the change in luminescent color of the two-dimensional perovskite LPbI4 single crystal in Example 6 after changing the laser pulse frequency. DETAILED DESCRIPTION

[0040] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0041] The present invention provides a luminescence control method for a DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths. The two-dimensional perovskite LPbI4 single crystal is a two-dimensional DJ-type perovskite single crystal. The luminescence color is controlled by excitation of pulsed excitation light with different power densities or pulse frequencies. The luminescence color changes continuously from blue to red as the excitation light pulse power or frequency increases; the luminescence color changes continuously from red to blue as the excitation light power density or pulse frequency decreases.

[0042] The pulse frequency of the pulsed excitation light is as follows: the repetition frequency range of the excitation light is 0.01–41 MHz, the laser single pulse energy at different repetition frequencies is consistent, and the laser single pulse energy is 3.5 μJ cm during the fluorescence spectrum test. -2 , the laser single pulse energy in bright field imaging is 7 μJ cm -2 and 10.5 μJ cm -2 .

[0043] The power density of the pulsed excitation light is: during fluorescence spectrum testing, the excitation light repetition frequency is 2MHz, and the variable laser power range is 0.001-10uw; during bright field imaging, the laser repetition frequency is 5MHz, and the variable laser power range is 0.001-20uw; it is divided into wide field and fixed point excitation, and the excitation wavelength is 405nm.

[0044] The method for preparing two-dimensional perovskite LPbI4 single crystals based on organic ligands with different chain lengths is a chemical reaction between solid PbI2 and organic ligands in HI solution. The growth process of the two-dimensional perovskite LPbI4 single crystal is controlled by adjusting the proportion of ions in the solution, the reaction heating temperature, and the annealing temperature and time, and the single crystals are finally prepared.

[0045] The organic ligand is alkyl diamine, and the morphology of the two-dimensional perovskite LPbI4 single crystal is regular and geometrical, wherein the geometrical shape of the two-dimensional perovskite LPbI4 single crystal is related to the chain length of the alkyl diamine.

[0046] The specific preparation includes the following steps:

[0047] (1) Mix solid PbI2 and organic ligand in a molar ratio of (0.5-4):1 in a reaction bottle, add hydroiodic acid in small amounts and dropwise into the reaction bottle several times, and heat and stir at 80-180°C until the solid reactant is completely dissolved;

[0048] (2) gradually and uniformly cooling the solution in step (1) until the concentration reaches a saturated state and perovskite solid is precipitated to obtain a mother solution;

[0049] (3) Place the coverslip that has been cleaned by ethanol ultrasonication and plasma cleaning on a heating table, use a cotton swab to take a small amount of the mother solution in step (2), apply it on the coverslip, anneal at 50-120°C, and let it stand for 5-30 seconds until it is completely dry, thereby obtaining a two-dimensional perovskite LPbI4 single crystal with regular morphology.

[0050] In addition, it should be understood that although this specification is described according to the implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. These other implementation modes are also covered within the protection scope of the present invention.

[0051] In this embodiment, a UV-visible absorption spectrometer (UV-6000PC, Shanghai Yuanxi Instrument Co., Ltd.) was used to test the UV-visible absorption spectrum; a 405nm laser (PIXEA-405, Aurea Technology, France) was used as the excitation light source, and a spectrometer (SpectraPro-2300i, Acton Research Co., USA) was used to collect the fluorescence spectrum. The crystal structure of the material was analyzed by X-ray diffraction (XRD) spectroscopy, the morphology and size of the material were observed by field emission scanning electron microscopy (FESEM) and dark field optical microscopy, and the microscopic crystal structure was analyzed by transmission electron microscopy (TEM).

[0052] Example 1

[0053] This embodiment provides a two-dimensional perovskite LPbI4 single crystal, and the preparation process is as follows: solid PbI2 and 1,4-diamine with a molar ratio of 2:1 are placed in a reaction bottle, HI is added in small amounts and multiple times, and heated and stirred at 160°C until the solid reactant is just completely dissolved, and gradually cooled evenly until the solution concentration is saturated and perovskite solid is precipitated. Place a cover glass that has been cleaned by ethanol ultrasound and plasma cleaning on an 80°C heating table, dip a small amount of mother liquor with a cotton swab, paint it on the cover glass, and let it stand for 30 seconds until it is completely dry, and a two-dimensional perovskite LPbI4 single crystal can be produced.

[0054] The crystal is shown in the microscope image and SEM image respectively. Figure 1 as well as Figure 3 As shown in the picture, the crystal has a regular hexagonal shape. The UV-visible absorption spectrum and steady-state fluorescence spectrum of the crystal are shown in Figure 5 As shown, its exciton resonance absorption peak is 496nm, and the central wavelength of the exciton emission peak is 506nm. In addition to the exciton luminescence peak, a wide spectrum luminescence with a wavelength center of 663nm appears in the long-wave band, which belongs to defect state luminescence.

[0055] Example 2

[0056] This embodiment provides a two-dimensional perovskite LPbI4 single crystal, and the preparation process is as follows: solid PbI2 and 1,6-hexanediamine with a molar ratio of 2:1 are placed in a reaction bottle, HI is added in small amounts and multiple times, and heated and stirred at 150°C until the solid reactant is just completely dissolved, and gradually cooled evenly until the solution concentration is saturated and perovskite solid is precipitated. Place a cover glass that has been cleaned by ethanol ultrasound and plasma cleaning machine on an 80°C heating table, dip a small amount of mother liquor with a cotton swab, paint it on the cover glass, and let it stand for 30 seconds until it is completely dry, and a two-dimensional perovskite LPbI4 single crystal can be produced.

[0057] The crystal is shown in the microscope image and SEM image respectively. Figure 2 as well as Figure 4 As shown in the picture, the crystal has a regular shape and is quadrilateral. The UV-visible absorption spectrum and steady-state fluorescence spectrum of the crystal are shown in Figure 6 As shown (normalized to the exciton peak), the exciton resonance absorption peak is 486nm, the central wavelength of the exciton emission peak is 496nm, and in addition to the exciton luminescence peak, a wide spectrum luminescence with a wavelength center of 666nm appears in the long-wave band, which belongs to defect state luminescence.

[0058] Example 3

[0059] This example uses the two-dimensional perovskite LPbI4 single crystal prepared in Example 1, and adjusts its luminescent color by changing the power density of the excitation light. The repetition frequency is 2MHz during fluorescence spectrum testing, and the laser power range is changed to 0.001-10uw; the repetition frequency is 5MHz during bright field imaging, and the laser power range is changed to 0.001-20uw; it is divided into wide field and fixed point excitation, and the excitation wavelength is 405nm. The power-dependent normalized fluorescence emission spectrum of the crystal is as follows Figure 7 As shown in the figure (normalized to the exciton peak), as the excitation power increases, the defect luminescence ratio increases first, reaching 3.57 mJ cm -2 The maximum value is reached when the excitation power increases, and then the proportion of defect state emission gradually decreases with the increase or decrease of the excitation power. The photo of the change of emission color after changing the excitation light power density is shown in the figure. Fig.11 As shown in the picture, as the power density increases, the crystal light color changes continuously from blue to red.

[0060] Example 4

[0061] This example uses the two-dimensional perovskite LPbI4 single crystal prepared in Example 2 to adjust its luminescent color by changing the power density of the excitation light. The repetition frequency is 2MHz during fluorescence spectrum testing, and the laser power range is changed to 0.001-10uw; the repetition frequency is 5MHz during bright field imaging, and the laser power range is changed to 0.001-20uw; it is divided into wide field and fixed point excitation, and the excitation wavelength is 405nm. The power-dependent normalized fluorescence emission spectrum of the crystal is as follows Figure 8 As shown in the figure (normalized to the exciton peak), as the excitation power increases, the defect luminescence ratio increases first, reaching 3.18 mJ cm -2 The maximum value is reached when the excitation power increases, and then the proportion of defect state emission gradually decreases with the increase or decrease of the excitation power. The photo of the change of emission color after changing the excitation light power density is shown in the figure. Fig.12 As shown in the picture, as the power density increases, the crystal light color changes continuously from blue to red.

[0062] Example 5

[0063] This example uses the two-dimensional perovskite LPbI4 single crystal prepared in Example 1, and adjusts its luminescent color by changing the pulse frequency of the excitation light. The repetition frequency range of the excitation light is 0.01-41 MHz, and the laser single pulse energy with different repetition frequencies is consistent. The laser single pulse energy in the fluorescence spectrum test is 3.5 μJ cm -2 The single laser pulse energy was 7 and 10.5 μJ cm in bright field imaging. -2 The frequency-dependent normalized fluorescence emission spectrum of the crystal is Fig. 9 As shown (normalized to the exciton peak), as the excitation light power increases, the proportion of the broad spectrum caused by defect states gradually increases.

[0064] The photo of the crystal changing the color of light after changing the laser pulse frequency is shown in the figure. Fig.13 As shown, as the pulse frequency increases, the crystal light color changes continuously from blue to red.

[0065] Example 6

[0066] This example uses the two-dimensional perovskite LPbI4 single crystal prepared in Example 2, and adjusts its luminescent color by changing the pulse frequency of the excitation light. The repetition frequency range of the excitation light is 0.01-41 MHz, and the laser single pulse energy with different repetition frequencies is consistent. The laser single pulse energy in the fluorescence spectrum test is 3.5 μJ cm -2 The single laser pulse energy was 7 and 10.5 μJ cm in bright field imaging. -2 The frequency-dependent normalized fluorescence emission spectrum of the crystal is Fig.10 As shown (normalized to the exciton peak), as the excitation light power increases, the proportion of the broad spectrum caused by defect states gradually increases.

[0067] The photo of the crystal changing the color of light after changing the laser pulse frequency is shown in the figure. Fig.14 As shown, as the pulse frequency increases, the crystal light color changes continuously from blue to red.

[0068] Therefore, the present invention provides a DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths, and a preparation method and a luminescence regulation method thereof. Alkyl diamine ligands of different chain lengths are used to prepare a two-dimensional DJ-type perovskite LPbI4 single crystal with n=1. The preparation method introduces defects, thereby achieving two-color emission without doping, and the luminescence color can be regulated by changing the excitation light power and frequency.

[0069] 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 they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for regulating the luminescence of DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths, characterized in that: The two-dimensional perovskite LPbI4 single crystal uses pulsed excitation light with different power densities or pulse frequencies to regulate the luminescence color. The luminescence color changes continuously from blue to red as the excitation light pulse power or frequency increases, and the luminescence color is reversible.

2. According to claim 1, a luminescence control method of a DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths, characterized in that: The pulse frequency of the pulsed excitation light is: the excitation light repetition frequency range is 0.01–41 MHz, the laser single pulse energy with different repetition frequencies is consistent, and the laser single pulse energy is 3.5 μJ cm during the fluorescence spectrum test -2 , the laser single pulse energy in bright field imaging is 7 μJ cm -2 and 10.5 μJ cm -2 .

3. The luminescence control method of a DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths according to claim 1, characterized in that: The power density of the pulsed excitation light is as follows: in fluorescence spectrum testing, the excitation light repetition frequency is 2 MHz, and the variable laser power range is 0.001-10 uw; in bright field imaging, the laser repetition frequency is 5 MHz, and the variable laser power range is 0.001-20 uw; it is divided into wide field and fixed point excitation, and the excitation wavelength is 405 nm.

4. A DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths, characterized in that: The luminescence color of the two-dimensional perovskite LPbI4 single crystal is controlled by the luminescence control method described in any one of claims 1 to 3, and the two-dimensional perovskite LPbI4 single crystal is a two-dimensional DJ-type perovskite single crystal.

5. A method for preparing DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths as claimed in claim 4, characterized in that: The two-dimensional perovskite LPbI4 single crystal is finally prepared by an ion exchange reaction between solid PbI2 and an organic ligand in a HI solution, and by controlling the growth process of the two-dimensional perovskite LPbI4 single crystal by adjusting the proportion of ions in the solution, the reaction heating temperature, and the annealing temperature and time.

6. The method for preparing a DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths according to claim 5, characterized in that: The organic ligand is alkyl diamine, and the morphology of the two-dimensional perovskite LPbI4 single crystal is regular and geometrical in shape, and the geometrical shape of the two-dimensional perovskite LPbI4 single crystal is related to the chain length of the alkyl diamine.

7. The method for preparing a DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths according to claim 5, characterized in that: The specific preparation includes the following steps: (1) Mix solid PbI2 and organic ligands in a reaction bottle, add small amounts of hydroiodic acid to the reaction bottle several times, and heat and stir until the solid reactants are completely dissolved; (2) gradually and uniformly cooling the solution in step (1) until the concentration reaches a saturated state and perovskite solid is precipitated to obtain a mother solution; (3) Place the coverslip that has been cleaned by ethanol ultrasonication and plasma cleaning on a heating table, use a cotton swab to take a small amount of the mother solution in step (2), apply it on the coverslip for annealing, and let it stand for 5-30 seconds until it is completely dry to obtain a two-dimensional perovskite LPbI4 single crystal with regular morphology.

8. The method for preparing DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths according to claim 7, characterized in that: In step (1), the molar ratio of solid PbI2 to organic ligand is (0.5-4):

1.

9. The method for preparing DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths according to claim 7, characterized in that: The heating and stirring temperature in step (1) is 80-180°C.

10. The method for preparing DJ-type two-dimensional perovskite LPbI4 single crystal based on organic ligands of different chain lengths according to claim 7, characterized in that: The coverslip annealing temperature in step (3) is 50–120°C.

Images