Controllable Preparation Method of Two-Dimensional Tin-Based Perovskite and Its Application in Optical Pumping

Abstract

The present invention provides a controllable preparation method of two-dimensional tin-based perovskite and its application in optical pumping. A crystal growth solution containing tin iodide and an organic iodide salt ligand is added to a container containing a mixed solvent of hydroiodic acid, hypophosphorous acid and an auxiliary organic solvent. After sealing the container, it is heated until the solution in the container becomes clear. The container is transferred to a temperature-controlled furnace and the temperature is programmed to decrease until the solution in the container is cooled to room temperature, and high-purity two-dimensional tin-based perovskite with different ligands and adjustable n value is precipitated. By controlling the polarity of the solution, this preparation method can obtain high-purity two-dimensional tin-based perovskite containing different organic ligands, and at the same time can precisely control the n value of the two-dimensional perovskite (the n value represents the thickness of the inorganic layer). Under femtosecond laser excitation, the mechanically exfoliated nanosheets themselves act as a resonant cavity, realizing tunable laser emission without an external resonant cavity.

Description

Technical Field

[0001] The present invention relates to the field of materials science, and particularly to a controllable preparation method of two-dimensional tin-based perovskite and its application in optical pumping. Background Art

[0002] Two-dimensional van der Waals layered semiconductor materials, such as transition metal dichalcogenides and black phosphorus, have been widely used in optics, electronics, and optoelectronics. They can be easily mechanically exfoliated into thin flakes, ensuring a super-smooth surface without dangling bonds and enabling precise control of the thickness at the sub-nanometer level. As a class of emerging van der Waals semiconductors, two-dimensional van der Waals layered semiconductor materials have high luminescence yields and widely tunable band structures. Two-dimensional Ruddlesden-Popper (RP) halide perovskites L2A n- 1M n X 3n+1 (L: large organic cation, A: small organic cation, M: divalent metal cation, X: halide, n: the number of metal halide octahedra along the out-of-plane direction in each layer of RP halide perovskite) have received great attention and rapid development.

[0003] Different from transition metal dichalcogenides, two-dimensional halide perovskites are organic-inorganic hybrid materials. The semiconductor properties of two-dimensional halide perovskites are mainly dominated by inorganic metal halide octahedron layers. A relatively large distance is formed between adjacent inorganic layers through organic spacer ligands, reducing the interlayer coupling and retaining the direct bandgap property in halide perovskites of any thickness. In addition, the organic ligands act as a molecular-level encapsulation layer, reducing the interaction between polar octahedra and environmental humidity / oxygen, resulting in better environmental stability than three-dimensional halide perovskites.

[0004] Currently, two-dimensional lead halide perovskites are usually used as the active layer or passivation layer of optoelectronic devices, and two-dimensional perovskite lasers have gradually attracted attention. At present, mechanically exfoliated two-dimensional lead-based perovskites (n>1) have shown lasing without external holes in the visible region. However, it is difficult to achieve lasing in two-dimensional lead-based perovskites (n = 1) without an external resonant cavity. In other words, the lasing performance of two-dimensional lead-based perovskites (n = 1) has only been reported in bulk crystals or with the aid of an external cavity, which is considered to be the result of high Auger recombination and strong exciton-phonon coupling strength.

[0005] Compared with two-dimensional lead-based perovskites, two-dimensional tin-based perovskites, as a representative non-lead perovskite material, have attracted extensive attention in the academic community due to their relatively small optical bandgap, relatively small effective mass of carriers, and relatively low toxicity compared to lead-based perovskites. However, it is still challenging to control the n value in the current preparation methods of two-dimensional tin-based perovskites and to synthesize pure-phase RP tin halide perovskites, and the corresponding optoelectronic properties have also lacked research. Summary of the Invention

[0006] The present solution provides a controllable preparation method of two-dimensional tin-based perovskites and their application in optical pumping. By introducing an organic solvent miscible with hydroiodic acid and hypophosphorous acid to control the polarity of the mixed solvent, and using different organic ligands as raw materials to complete the preparation of high-purity two-dimensional tin-based perovskites, the n value of two-dimensional tin-based perovskites can also be accurately controlled, and it has a wide range of applications in optical pumping.

[0007] To achieve the above object, the present solution provides a controllable preparation method of two-dimensional tin-based perovskites, including the following steps:

[0008] Prepare a growth crystal; mix tin iodide and an organic iodide salt ligand in a set ratio;

[0009] Prepare a mixed solvent: mix hydroiodic acid, hypophosphorous acid and an auxiliary organic solvent in a set ratio:

[0010] Dissolution: Add the growth crystal into a container containing the mixed solvent, seal the container and heat it until the solution in the container becomes clear;

[0011] Cooling crystallization: Transfer the container to a temperature control furnace and set a programmed temperature drop until the solution in the container is cooled to room temperature, and two-dimensional tin-based perovskites are precipitated.

[0012] In some embodiments, the organic iodide salt ligand is selected from any one of n-butylammonium iodide (BAI), phenethylammonium (PEAI), 2-ethylamine-bithiophene iodide (2TI), 2-ethylamine-terthiophene iodide (3TI), or a combination of any one of n-butylammonium iodide (BAI), phenethylammonium (PEAI), 2-ethylamine-bithiophene iodide (2TI), 2-ethylamine-terthiophene iodide (3TI) and methyl hydrogen iodide salt (MAI).

[0013] In the embodiments of the present solution, the organic iodide salt ligand and tin iodide SnI2 are mixed as organic ligands in a set ratio to obtain a growth crystal, and the preparation of two-dimensional tin-based perovskites with different n values is realized through the selection of the growth crystal.

[0014] In some specific embodiments, the organic iodide salt ligand is selected as n-butylammonium iodide (BAI), and the grown crystal is (BA)2SnI4. When the molar ratio of n-butylammonium iodide (BAI) to tin iodide (SnI2) is 9:8, the single crystal of the grown crystal is (BA)2SnI4.

[0015] In some other specific embodiments, the organic iodide salt ligands are selected as n-butylammonium iodide (BAI) and methylammonium iodide (MAI). Different single crystals of grown crystals are obtained corresponding to different molar ratios of n-butylammonium iodide (BAI), methylammonium iodide (MAI) and tin iodide (SnI2), which are (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 3).

[0016] When the molar ratio of n-butylammonium iodide (BAI), methylammonium iodide (MAI) and tin iodide (SnI2) is 43:20:59, the single crystal is (BA)2MASn2I7; when the molar ratio of n-butylammonium iodide (BAI), methylammonium iodide (MAI) and tin iodide (SnI2) is 43:46:59, the single crystal is (BA)2MA2Sn3I 10 ; when the molar ratio of n-butylammonium iodide (BAI), methylammonium iodide (MAI) and tin iodide (SnI2) is 2:5:3, the single crystal is (BA)2MA3Sn4I 13 .

[0017] In some other specific embodiments, the organic iodide salt ligand is selected as phenethylammonium iodide (PEAI), and the obtained crystal is (PEA)2SnI 4。 When the molar ratio of phenethylammonium iodide (PEAI) to tin iodide (SnI2) is 4:1, the obtained crystal is (PEA)2SnI4.

[0018] In some other specific embodiments, the organic iodide salt ligands are selected as phenethylammonium iodide (PEAI) and methylammonium iodide (MAI), and the obtained crystal is (PEA)2MASn2I7. When the molar ratio of phenethylammonium iodide (PEAI), methylammonium iodide (MAI) and tin iodide (SnI2) is 17:4:4, the obtained crystal is (PEA)2MASn2I7.

[0019] In some other specific embodiments, the organic iodide salt ligand is selected as 2-ethylamine-bithiophene iodide (2TI), and the obtained crystal is (2T)2SnI4; when the molar ratio of 2-ethylamine-bithiophene iodide (2TI) to tin iodide (SnI2) is 1:10, the obtained crystal is (2T)2SnI4.

[0020] In some other specific embodiments, the organic iodide salt ligands are selected as 2-ethylamine-bithiophene iodide (2TI) and methylammonium iodide (MAI), and the obtained crystal is (2T)2MASn2I 7。When the molar ratio of 2-ethylamine-bithiophene iodide 2TI, methyl hydroiodide MAI, and tin iodide SnI2 is 3:76:25, the resulting crystal is (2T)2MASn2I7.

[0021] In some other specific embodiments, the organic iodide salt ligand is selected as 2-ethylamine-terthiophene iodide 3TI, and the resulting crystal is (3T)2SnI 4。 When the molar ratio of 2-ethylamine-terthiophene iodide 3TI and tin iodide SnI2 is 1:6, the resulting crystal is (3T)2SnI4.

[0022] In some other specific embodiments, the organic iodide salt ligand is selected as 2-ethylamine-terthiophene iodide 3TI and methyl hydroiodide MAI, and the resulting crystal is (3T)2MASn2I7. When the molar ratio of 2-ethylamine-terthiophene iodide 3TI, methyl hydroiodide MAI, and tin iodide SnI2 is 5:1006:30, the resulting crystal is (3T)2MASn2I7.

[0023] This solution not only realizes the preparation of two-dimensional tin-based perovskites with different n values by growing crystals composed of organic iodide salts and tin iodide with different molar ratios, but also reduces the polarity of the mixed solvent by introducing an organic solvent miscible with hydroiodic acid and hypophosphorous acid, and thus high-purity two-dimensional tin-based perovskites can be prepared.

[0024] Regarding the selection of the auxiliary organic solvent in the mixed solvent of this solution, it is an organic solvent miscible with hydroiodic acid and hypophosphorous acid, and is selected as isopropanol or ethanol. This solution adjusts the polarity of the mixed solvent by adding other organic solvents to ensure that the organic ligands and inorganic salts in the growing crystals can be completely dissolved.

[0025] The selection of the growing crystals and the mixed solvent in this solution is shown in Table 1 below. The molar ratios of each formula in this table correspond to high-purity two-dimensional tin-based perovskites:

[0026] Table 1 Two-dimensional tin-based perovskite single crystal formula table

[0027]

[0028]

[0029] It should be noted that this solution can obtain high-purity two-dimensional tin-based perovskites within a certain range by adjusting the molar ratios of each formula in the growing crystals and the mixed solvent. The purity of the two-dimensional tin-based perovskites obtained in this solution is controlled above 95%.

[0030] In addition, the interior of the container mixed with the mixed solvent needs to be kept clean, have good airtightness, and be heat-resistant. In the cooling crystallization step, as the temperature decreases, the solubility of two-dimensional tin-based perovskite in the solution decreases, and then crystals are cooled out from the supersaturated solution to obtain two-dimensional tin-based perovskite.

[0031] In a second aspect, the present solution provides a controllable preparation method of the above two-dimensional tin-based perovskite prepared according to the above controllable preparation method of two-dimensional tin-based perovskite.

[0032] In a third aspect, the present solution provides an application method of the above controllable preparation method of two-dimensional tin-based perovskite in optical pumping, including the following steps:

[0033] Take out the two-dimensional tin-based perovskite prepared by the above controllable preparation method in an inert environment and dry it to obtain two-dimensional tin-based perovskite crystals;

[0034] Place the side with metallic luster of the two-dimensional tin-based perovskite crystal on the tape, repeatedly fold the tape along the same direction to obtain a tape wrapped with the two-dimensional tin-based perovskite crystal, and cover the tape on Si / SiO2 to obtain a sample;

[0035] Place the sample in a low-temperature chamber and set it to be stable in a low-temperature environment for a period of time to obtain a stable sample;

[0036] Under different test conditions, use a pump laser to excite the stable sample and collect the emitted laser signal.

[0037] It should be noted that the two-dimensional tin-based perovskite obtained in this aspect can observe a laser signal when excited by a femtosecond pump laser after being cooled to a low temperature after mechanical exfoliation, and the present solution provides a test of the response of the two-dimensional tin-based perovskite to pump light under different test conditions.

[0038] During the process of taking out the two-dimensional tin-based perovskite in an inert environment, it is necessary to ensure that it does not come into contact with air to avoid being damaged after contacting air.

[0039] In addition, in the present solution, the low-temperature chamber is first evacuated for more than half an hour, and then the sample is placed in the low-temperature chamber and set to be stable in a low-temperature environment for a period of time. The stable time is controlled to be more than half an hour. In some specific embodiments, the low-temperature environment in the present solution is controlled to be 83K. This is because the thermal vibration of the material weakens and the photoluminescence becomes stronger at low temperatures, which is beneficial to studying the laser performance of two-dimensional tin-based perovskite.

[0040] In some implementations, when it is necessary to test the laser signal at different temperatures, ensure that the laser signal is collected only after the temperature is stable.

[0041] Fourthly, this solution provides an application method of a controllable preparation method of two-dimensional tin-based perovskite in optical pumping, including: mechanically exfoliating the prepared two-dimensional perovskite and using it as the resonant cavity of an optical pumping laser, and the optical pumping laser can achieve tunable laser emission without an external resonant cavity under the excitation of pump light.

[0042] Compared with the prior art, this technical solution has the following characteristics and beneficial effects:

[0043] By selecting different organic ligands and the polarity of the mixed solvent, the preparation of high-purity two-dimensional tin-based perovskite containing organic ligands is successfully synthesized, and the n value of two-dimensional tin-based perovskite can also be accurately controlled. This solution is widely applicable to the synthesis of various two-dimensional tin-based perovskites with high n values; in addition, this solution has successfully realized optical pumping laser based on two-dimensional tin-based perovskite. Even at room temperature, two-dimensional tin-based perovskite can be applied to a pump laser through a laser signal, so as to achieve tunable laser emission without an external resonant cavity. Description of the Drawings

[0044] Figure 1 Powder XRD data diagram of (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4);

[0045] Figure 2 Powder XRD data diagram of (L)2MA n-1 Sn n I 3n+1 (n = 1 - 2);

[0046] Figure 3 PL data diagram of (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4);

[0047] Figure 4 PL data diagram of (L)2MA n-1 Sn n I 3n+1 (n = 1 - 2);

[0048] Figure 5 UV-Vis data diagram of (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4);

[0049] Figure 6 UV-Vis data diagram of (L)2MA n-1 Snn I 3n+1 (n = 1 - 2) UV-Vis data graph;

[0050] Figure 7 (BA)2MA prepared by the present invention n-1 Sn n I 3n+1 (n = 2 - 4) Optical pump laser data graph;

[0051] Figure 8 (L)2MA prepared by the present invention n-1 Sn n I 3n+1 (n = 1 - 2) Optical pump laser data graph;

[0052] Figure 9 PL data graph of (2T)2PbI4 prepared by the present invention (excited by the same light source);

[0053] Figure 10 PL data graph of (3T)2PbI4 prepared by the present invention (excited by the same light source);

[0054] Figure 11 Optical pump laser data graph of (L)2MASn2I7 prepared by the present invention;

[0055] Figure 12 Optical pump laser threshold data graph of (L)2MASn2I7 prepared by the present invention;

[0056] Figure 13 Variable temperature optical pump laser data graph of (3T)2MASn2I7 prepared by the present invention;

[0057] Figure 14 is (BA)2MA prepared by the present invention n-1 Sn n I 3n+1 (n = 1 - 3) AFM images and height profile graphs. Detailed implementation manners

[0058] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0059] It is understood that the term "one" should be understood as "at least one" or "one or more". That is, in one embodiment, the number of an element can be one, while in other embodiments, the number of the element can be multiple. The term "one" should not be understood as a limitation on the quantity.

[0060] Example 1 (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4) Preparation and testing;

[0061] (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4) Preparation: Take tin iodide and n-butylammonium iodide BAI and methylammonium iodide MAI and mix them to obtain the growth crystal. Mix hydroiodic acid and hypophosphorous acid to obtain the mixed solvent. Mix the growth crystal and the mixed solvent in a container and ensure that the container is sealed well to prevent air from entering. The mixing molar ratio is shown in Table 2; Place the container in a heating furnace and continuously heat it until the solution becomes clear; Transfer the container to a temperature control furnace and set the program to cool down. After cooling to room temperature, (BA)2MA precipitates. n-1 Sn n I 3n+1 (n = 1 - 4) Two-dimensional tin-based perovskite;

[0062] Take out the obtained two-dimensional tin-based perovskite in an inert environment, dry it. During the process of collecting the crystals, do not contact air. Take out the crystal with the metallic luster side and place it on the tape, fold it back and forth repeatedly in one direction, and then cover the tape on Si / SiO2; Place the sample in a low-temperature chamber, set the temperature to 83K, and stabilize for a long time; Use a pump laser to excite the sample, collect the emitted laser signal, and when measuring the laser signal at different temperatures, wait until the temperature is stable before proceeding to the next data collection.

[0063] Table 2 (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4) Preparation formula table

[0064]

[0065] (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4) Testing: Perform powder XRD testing on the prepared (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4) two-dimensional tin-based perovskite to obtain the powder XRD data graph as Figure 1 shown, perform PL testing to obtain the PL data graph asFigure 3 As shown, the UV-Vis test gives the UV-Vis as Figure 5 As shown, the data graph of the optical pumping test is as Figure 7 shown. (n = 1 - 4, abbreviated as BA Sn n = 1, BA Sn n = 2, BA Sn n = 3, and BA Sn n = 4 in the test graph). From Figure 1 it can be seen that (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4) has a very high purity. From Figure 3 and Figure 5 it can be seen that (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4) has a strong exciton emission; from Figure 7 it can be seen that the two-dimensional tin-based perovskite prepared from (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4) can show the signal of optical pumping laser in optical pumping. For (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 3), the AFM test gives the graph as Figure 14 shown.

[0066] In addition, the crystal structure of (BA)2MA n-1 Sn n I 3n+1 (n = 1 - 4) is tested and the results are shown in Table III - Table VI as follows:

[0067] Table III Crystal structure data of (BA)2MA n-1 Sn n I 3n+1 (n = 1)

[0068]

[0069]

[0070]

[0071] Table IV Crystal structure data of (BA)2MA n-1 Sn n I 3n+1 (n = 2)

[0072]

[0073]

[0074] Table 5 (BA)2MA n-1 Sn n I 3n+1 Crystal structure data of (n = 3)

[0075]

[0076]

[0077]

[0078] Table 6 (BA)2MA n-1 Sn n I 3n+1 Crystal structure data of (n = 4)

[0079]

[0080]

[0081] From the data in Table 3 to Table 6, it can be seen that there is no disorder in the Sn-I lattice of (BA)2SnI4. The Uij components of the ADPs of all C and N atoms (ISOR 0.001), and the SIMU 0.001 command of Shelxl are used to maintain similar anisotropic temperature factors; the crystal structure of (BA)2MASn2I7 is refined as a twin, consisting of inversion twins in the structure. The combination of the twin transformation matrix and the condition of the twin law (-1.0, 0.0, 0.0, -0.0, -1.0, 0.0, 0.0, -1.0) with the inversion twin results in a BASF value of 0.2(3). Similar to the Sn-I inorganic fragment of (BA)2SnI4, there is no disorder in the Sn-I lattice. According to the previous reasonable BA cation model, all BA cations are constrained to have similar and reasonable geometries. Through the ISOR 0.001 and DELU 0.001 commands of Shelxl, the ADPs and disordered C and N atoms are suppressed to be similar. The SIMU 0.001 command of Shelxl suppresses the similar anisotropic temperature factors and Uij components of C and N. Using the DFIX 0.01 of the Shelxl instruction, the distances of C—N and C—C are constrained to form a reasonable organic geometry. According to the C-N and C-C distances of the previous general BA cations, the specific commands are as follows: The C-N bond length is restricted to t; (BA)2MA2Sn3I 10The crystal structure is refined to twins, consisting of inversion twins in the structure. The twinning transformation matrix satisfies the conditions of the twin law (-1.0, 0.0, 0.0, -0.0, -1.0, 0.0, 0.0, -1.0). Combining with the inversion twin results in a BASF value of 0.8(3). Different from the Sn-I inorganic fragments of (BA)2SnI4 and (BA)2MASn2I7, there is a small amount of disorder in the Sn-I lattice, and the I1 and I6 atoms are refined as disordered. The occupancies of all disordered I atoms are freely refined to I1(0.8913) and I6(0.1114). According to the previous reasonable BA cation model, all BA cations are constrained to have similar and reasonable geometries. Through the ISOR 0.001 and DELU 0.001 commands of Shelxl, the ADPs and disordered C, N atoms are suppressed to be similar. The SIMU 0.001 command of Shelxl suppresses the similar anisotropic temperature factors and Uij components of C, N, and the distances of C—N and C—C are constrained by D to form a reasonable organic geometry; (BA)2MA3Sn4I 13 The crystal structure is refined to twins, consisting of inversion twins in the structure. The twinning transformation matrix satisfies the conditions of the twin law (-1.0, 0.0, 0.0, -0.0, -1.0, 0.0, 0.0, -1.0) combined with the inversion twin results in a BASF value of 0.1(3), similar to the Sn-I inorganic fragment of (BA)2MA2Sn3I 10 There is a small amount of disorder in the Sn-I lattice. The I6 and I8 atoms are refined as disordered. The occupancies of all disordered I atoms are freely refined to I6(0.08731 and I8(0.0.91088). In fact, according to the previous reasonable model, the BA and MA cations are restricted to have similar and reasonable geometries. Through the ISOR 0.001 and DELU 0.001 commands of Shelxl, the ADPs and disordered C, N atoms are suppressed to be similar. The SIMU 0.001 command of Shelxl suppresses the similar anisotropic temperature factors and Uij components of C, N. The reasonable distances of C-N and C-C with the organic fragment are suppressed by DFIX 0.01 of S.

[0082] Example 2 (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 2) Preparation and testing;

[0083] (PEA)2MA n-1 Sn n I 3n+1(n = 1 - 2) Preparation: Take tin iodide, phenethylammonium (PEAI), and methylammonium iodide (MAI) and mix them to obtain the crystal for growth. Mix hydroiodic acid and hypophosphorous acid to obtain the mixed solvent. Mix the crystal for growth and the mixed solvent in a container and ensure that the container is sealed well to prevent air from entering. The mixing molar ratios are shown in Table VII. Place the container in a heating furnace and continuously heat it until the solution becomes clear. Transfer the container to a temperature-controlled furnace and set the program for cooling. After cooling to room temperature, (PEA)2MA will precipitate. n-1 Sn n I 3n+1 (n = 1 - 2) Two-dimensional tin-based perovskite;

[0084] Take out the obtained two-dimensional tin-based perovskite in an inert environment, dry it. During the process of collecting the crystals, do not contact air. Take out the crystal with the metallic luster side and place it on the tape, and repeatedly fold it in one direction. Then cover the tape on Si / SiO2. Place the sample in a low-temperature chamber, set the temperature to 83K, and keep it stable for a long time. Use a pump laser to excite the sample, collect the emitted laser signal, and when measuring the laser signal at different temperatures, conduct the next data collection after the temperature is stable.

[0085] Table VII (PEA)2MA n-1 Sn n I 3n+1 Preparation formula table of (n = 1 - 2)

[0086]

[0087] In addition, this scheme tests the crystal structure of (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 2) and obtains the results shown in Tables VIII - IX as follows:

[0088] Table VIII (PEA)2MA n-1 Sn n I 3n+1 Crystal structure data of (n = 1)

[0089]

[0090]

[0091]

[0092] Table IX (PEA)2MA n-1 Sn n I 3n+1 Crystal structure data of (n = 2)

[0093]

[0094]

[0095] It can be seen from Table VIII to Table IX that the I3 and I5 atoms in the crystal structure of (PEA)2SnI4 are approximately located at pseudo-translation positions. There are two large residual electron peaks around I2 and I6. The I atoms in the Sn-I lattice are refined to a small amount of disorder along the ab plane, and there is no disorder in the iodide atoms along the

[001] direction. The distance between the large residual electron peak and Sn is close to the Sn-I bond length. According to the residual electron peak Using the free refinement method, it is defined as an I atom. The free-refined I atoms have occupancies of 0.086 and 0.075. To maintain electrical neutrality, the occupancies of the I5 and I3 atoms are changed to 0.07 and 0.93 respectively. The ADPs of the disordered I5 and I3 atoms are suppressed to be similar (ISOR 0.001 0.002 I5 I3); there is no disorder in the Sn-I lattice in the crystal structure of (PEA)2MASn2I7. However, in the organic part, some C and N atoms show unusual temperature factors and distances. To control all the organic phenethylammonium cations are restricted to have reasonable and similar geometries. The Uij components of the ADPs of all C and N atoms (ISOR 0.01), the SIMU 0.01 command of Shelxl is used to maintain similar anisotropic temperature factors. There are some deviations in the positions of the terminal C and N atoms, and their distances are reasonably restricted.

[0096] Example 3 (2T)MA2MA n-1 Sn n I 3n+1 (n = 1 - 2) Preparation and testing;

[0097] (2T)2MA n-1 Sn n I 3n+1 (n = 1 - 2) Preparation: Take tin iodide and 2-ethylamine-bithiophene iodide 2TI and methyl hydroiodide MAI and mix them to obtain the growing crystal. Mix hydroiodic acid, hypophosphorous acid and isopropanol to obtain the mixed solvent. Mix the growing crystal and the mixed solvent in a container and ensure that the container is sealed well to prevent air from entering. The mixing molar ratio is shown in Table X; Place the container in a heating furnace and continuously heat it until the solution becomes clear; Transfer the container to a temperature-controlled furnace and set the program to cool down. After cooling to room temperature, (2T)2MA precipitates n-1 Sn n I 3n+1 (n = 1 - 2) Two-dimensional tin-based perovskite;

[0098] Take out the obtained two-dimensional tin-based perovskite in an inert environment, dry it, and during the process of collecting the crystals, avoid contact with air. Take out the crystal with a metallic luster and place it on the tape, fold it back and forth repeatedly in one direction, and then cover the tape on Si / SiO2; place the sample in a low-temperature chamber, set the temperature to 83K, and keep it stable for a long time; use a pump laser to excite the sample, collect the emitted laser signal, and when measuring the laser signal at different temperatures, perform the next data collection after the temperature is stable.

[0099] Table X (2T)2MA n-1 Sn n I 3n+1 (n = 1 - 2) formulation

[0100]

[0101] In addition, the crystal structure of (2T)2SnI4 was tested in this solution and the results are shown in Table XI below:

[0102] Table XI Crystal structure data of (2T)2SnI4

[0103]

[0104]

[0105] It can be seen from Table XI that (2T)2SnI4 has been refined into inversion twins. The combination of the twin transformation matrix twinning law conditions (-1.0, 0.0, 0.0, -0.0, -1.0, 0.0, 0.0, -1.0) with inversion twins results in a BASF value of 0.4(3). The Sn-I part of the lattice was refined as disordered. If the occupancy of each disordered part is equal, the disordered Sn and I atoms have four-fold or higher symmetry for the Sn-I lattice. Due to the disorder observed in the Sn-I lattice, it causes disorder in the ammonium part of the 2T cation. All 2T cations are restricted to have similar and reasonable geometries.

[0106] Example 4 (3T)2MA n-1 Sn n I 3n+1 (n = 1 - 2) preparation and testing;

[0107] (3T)2MA n-1 Sn n I 3n+1(n = 1 - 2) Preparation: Take tin iodide and 2 - ethylamine - terthiophene iodide 3TI and methylammonium iodide MAI and mix them to obtain the crystal for growth. Mix hydroiodic acid, hypophosphorous acid, and ethanol to obtain a mixed solvent. Mix the crystal for growth and the mixed solvent in a container and ensure that the container is sealed well to prevent air from entering. The mixing molar ratios are shown in Table XII; Place the container in a heating furnace and continuously heat it until the solution becomes clear; Transfer the container to a temperature - controlled furnace and set a program for cooling. After cooling to room temperature, (3T)2MA will precipitate. n-1 Sn n I 3n+1 (n = 1 - 2) Two - dimensional tin - based perovskite;

[0108] Take out the obtained two - dimensional tin - based perovskite in an inert environment, dry it. During the process of collecting the crystals, do not contact air. Take out the crystal with the side having a metallic luster and place it on the tape. Fold it back and forth repeatedly in one direction, and then cover the tape on Si / SiO2; Place the sample in a low - temperature chamber, set the temperature to 83K, and keep it stable for a long time; Use a pump - pulsed laser to excite the sample, collect the emitted laser signal, and when measuring the laser signals at different temperatures, wait until the temperature is stable before proceeding to the next data collection step.

[0109] Table XII (3T)2MA n-1 Sn n I 3n+1 (n = 1 - 2) Formulation

[0110]

[0111] In this scheme, the crystal structure of (2T)2SnI4 is tested and the results are shown in Table XIII as follows:

[0112] Table XIII Crystal structure data of (2T)2SnI4

[0113]

[0114]

[0115] As can be seen from Table XII, the crystal structure of (3T)2SnI4 consists of pseudo-hexoctahedral twins (simulating monoclinic symmetry) and inversion twins. The combination of the twin transformation matrix and the conditions of the twin law (-1.0, 0.0, 0.0, -0.0, -1.0, 0.0, 0.0, -1.0) with the inversion twins results in a BASF value of 0.84(18), and this structure exhibits a pseudo-translation along the

[010] direction. The

[010] translational symmetry has been broken by the modulation of the Sn-I layer and the position of the terminal part of the 3T organic group; similar to the crystal structure of (2T)2SnI4, the Sn-I part of the lattice is refined as disordered. If the occupancy of each disordered part is equal, the disordered Sn and I atoms have a four-fold symmetry or higher symmetry for the Sn-I lattice.

[0116] Test of Example 2 - Example 4: The prepared (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 2), (2T)2MA n-1 Sn n I 3n+1 (n = 1 - 2), (3T)2MAMA n-1 Sn n I 3n+1 (n = 1 - 2) two-dimensional tin-based perovskite was subjected to powder XRD test to obtain the powder XRD data diagram as Figure 2 shown. The PL test was performed on (PEA)2MASn2I7, (2T)2MASn2I7, and (3T)2MASn2I7 two-dimensional tin-based perovskites to obtain the PL data diagram as Figure 4 shown. (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 2), (2T)2MAMA n-1 Sn n I 3n+1 (n = 1 - 2), (3T)2MA n-1 Sn n I 3n+1 (n = 1 - 2) two-dimensional tin-based perovskite was subjected to UV-Vis test to obtain UV-Vis as Figure 6 shown. The data diagram of the optical pumping test performed on (PEA)2SnI4, (2T)2SnI4, and (3T)2SnI4 two-dimensional tin-based perovskites is as Figure 8 shown. (In the test diagram, PEA Sn n = 1 or PEA Sn n = 2 represents (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 2), 2T Sn Sn = 1 or 2T Sn Sn = 2 represents (2T)2MAn-1 Sn n I 3n+1 (n = 1 - 2), 3T Sn Sn = 1 or 3T Sn Sn = 2 represents (3T)2MA n-1 Sn n I 3n+1 (n = 1 - 2). It can be seen from Figure 2 (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 2), (2T)2MA n-1 Sn n I 3n+1 (n = 1 - 2), (3T)2MA n-1 Sn n I 3n+1 (n = 1 - 2) The purity of two - dimensional tin - based perovskites is very high. It can be seen from Figure 4 and Figure 6 (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 2), (2T)2MA n-1 Sn n I 3n+1 (n = 1 - 2), (3T)2MA n-1 Sn n I 3n+1 (n = 1 - 2) has strong exciton emission; It can be seen from Figure 8 (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 2), (2T)2MA n- 1Sn n I 3n+1 (n = 1 - 2), (3T)2MA n-1 Sn n I 3n+1 (n = 1 - 2) The two - dimensional tin - based perovskites prepared can show the signal of optical - pumped laser in optical pumping.

[0117] In addition, this scheme also synthesizes two - dimensional lead - based perovskites (2T)2PbI4 and (3T)2PbI4 with the same ligand (the difference is that tin iodide is replaced by lead iodide) for optical - pumping test. The data graphs are as shown in Figure 9 and Figure 10 It can be seen that no laser signal is observed in two - dimensional lead - based perovskites.

[0118] In addition, optical pumping laser tests were performed on (BA)2MASn2I7, (PEA)2MASn2I7, (2T)2MASn2I7, and (3T)2MASn2I7 to obtain the optical pumping data graphs as Figure 11 shown, Figure 11 showing that by using different organic ligands, the laser emission position can be precisely regulated, which is due to the different degrees of lattice response to temperature. Optical pumping laser tests were performed on (BA)2MASn2I7, (PEA)2MASn2I7, (2T)2MASn2I7, and (3T)2MASn2I7 to obtain the optical pumping laser threshold data graphs as Figure 12 shown, Figure 12 showing that as the size of the organic ligand increases, the laser threshold gradually decreases, which is because of the reduced electron-phonon coupling and better stability. Temperature-dependent optical pumping tests were performed on (3T)2MASn2I7 at different temperatures to obtain the temperature-dependent optical pumping laser data graphs as Figure 13 shown, Figure 13 showing the temperature-dependent laser behavior of (3T)2MASn2I7. Even at room temperature, laser signals can be observed.

[0119] The present invention is not limited to the above best implementation manner. Anyone can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as it has the same or similar technical solutions as this application, it falls within the protection scope of the present invention.

Claims

1. A controllable preparation method of two-dimensional tin-based perovskite, characterized in that, It includes the following steps: Prepare a growing crystal; mix stannous iodide SnI2 and an organic iodide salt ligand in a set ratio; wherein the organic iodide salt ligand is selected from any one of n-butylammonium iodide, phenethylammonium, 2-ethylamine-bithiophene iodide, 2-ethylamine-terthiophene iodide, or a combination of any one of n-butylammonium iodide, phenethylammonium, 2-ethylamine-bithiophene iodide, 2-ethylamine-terthiophene iodide and methyl hydroiodide; Prepare a mixed solvent: mix hydroiodic acid, hypophosphorous acid and an auxiliary organic solvent in a set ratio, wherein the auxiliary organic solvent is selected as an organic solvent miscible with hydroiodic acid and hypophosphorous acid, and is selected as isopropanol or ethanol: Dissolution: Add the growing crystal into a container containing the mixed solvent, seal the container and heat it until the solution in the container becomes clear; Cooling crystallization: Transfer the container to a temperature control furnace and set a programmed temperature drop until the solution in the container is cooled to room temperature, and two-dimensional tin-based perovskite is precipitated; Among them, when the organic iodide salt is selected as n-butylammonium iodide, the grown crystal is (BA)2SnI4. When the organic iodide salts are selected as n-butylammonium iodide (BAI) and methylammonium iodide (MAI), the single crystal (BA)2MA is obtained. n-1 Sn n I 3n+1 , n = 1 - 3; when the organic iodide salt is selected as phenethylammonium, the crystal obtained is (PEA)2SnI4. When the organic iodide salts are selected as phenethylammonium and methylammonium iodide, the crystal obtained is (PEA)2MASn2I7; when the organic iodide salt is selected as 2-ethylamine-bithiophene iodide, the crystal obtained is (2T)2SnI4. When the organic iodide salts are selected as 2-ethylamine-bithiophene iodide and methylammonium iodide, the crystal obtained is (2T)2MASn2I7; when the organic iodide salt is selected as 2-ethylamine-terthiophene iodide, the crystal obtained is (3T)2SnI4. When the organic iodide salt ligand is selected as 2-ethylamine-terthiophene iodide (3TI) and methylammonium iodide (MAI), the crystal obtained is (3T)2MASn2I7.

2. Method for applying a controllable preparation method of two-dimensional tin-based perovskite in optical pumping, characterized in that, It includes the following steps: Take out the two-dimensional tin-based perovskite prepared by the controllable preparation method of two-dimensional tin-based perovskite according to claim 1 and dry it in an inert environment to obtain two-dimensional tin-based perovskite crystals; Place the side with metallic luster of the two-dimensional tin-based perovskite crystal on the tape, repeatedly fold the tape in the same direction to obtain a tape wrapped with the two-dimensional tin-based perovskite crystal, and cover the tape on Si / SiO2 to obtain a sample; Place the sample in a low-temperature chamber and set it to be stable in a low-temperature environment for a period of time to obtain a stable sample; Under different test conditions, use a pump laser to excite the stable sample and collect the emitted laser signal.

3. Method for applying a controllable preparation method of two-dimensional tin-based perovskite in optical pumping, characterized in that, It includes the following steps: After mechanically exfoliating the two-dimensional tin-based perovskite prepared by the controllable preparation method of two-dimensional tin-based perovskite according to claim 1, use it as the resonant cavity of a light-pumped laser, and this light-pumped laser can achieve tunable laser emission without an external resonant cavity under the excitation of a pump light.

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