Antioxidant preparation method of two-dimensional tin-based perovskite and application of two-dimensional tin-based perovskite in low-threshold long-life laser

Abstract

The invention discloses an anti-oxidation preparation method of two-dimensional tin-based perovskite and application of the two-dimensional tin-based perovskite in a low-threshold long-life laser. According to the method, a double-oxidation inhibition strategy is introduced, the large-size single crystal is synthesized by adopting a two-step growth method in an oxygen-free environment, and Sn < 2 + > oxidation is inhibited by adding electron donating molecules to interact with Sn < 2 + >. The method comprises the following specific steps: dissolving an organic ammonium salt, tin iodide and electron donating molecules in a mixed solvent of hydriodic acid and hypophosphorous acid, and crystallizing through an in-situ two-step supersaturated solution cooling method to obtain the high-purity two-dimensional tin-based perovskite single crystal. The nanosheet obtained through mechanical stripping is used as a gain medium and a resonant cavity, the laser threshold value as low as 0.88 mu J / cm < 2 > is achieved under femtosecond laser excitation, and excellent photoluminescence stability and laser stability are shown. According to the invention, the problems that tin-based perovskite is easy to oxidize and has many defects are solved, and a new idea is provided for the design of the lead-free perovskite nano laser.

Description

Technical Field

[0001] The invention relates to the field of lead-free perovskite photoelectric materials, and in particular to an oxidation-resistant preparation method of a two-dimensional tin-based perovskite and an application thereof in a low-threshold long-life laser. Background Art

[0002] Halide perovskites have become ideal candidate materials for future semiconductor lasers due to their excellent optoelectronic properties, direct bandgap characteristics, adjustable lattice constants and bandgap, and low-cost processing advantages. Compared with three-dimensional (3D) perovskites, two-dimensional (2D) halide perovskites have higher stability, fewer surface defects, and intrinsic quantum well structures. By regulating the two-dimensional Ruddlesden-Popper phase (L2A n-1 M n X 3n+1 , where L is an organic spacer cation, A is a small molecule organic cation, M is a metal cation, X is a halogen anion, and n represents the number of metal halide octahedral layers in a single layer of perovskite) can achieve precise control of the laser emission wavelength. In addition, two-dimensional tin-based halide perovskites have lower toxicity and narrower band gaps than lead-based perovskites, and have significant advantages in the development of lead-free red and near-infrared lasers. However, the rapid crystallization of two-dimensional tin-based perovskites and the Sn 2+ The easy oxidation property leads to a large number of lattice defects, which seriously limits the improvement of its laser performance. Existing studies have shown that although two-dimensional tin-based perovskites are easy to achieve optically pumped lasers, their oxidation problems and environmental instability pose major challenges to the life of the device. Although environmental instability can be alleviated by packaging technology, there is still a lack of systematic research on the stability of its photoluminescence (PL) and stimulated light emission. Summary of the invention

[0003] In view of the Sn 2+ In order to solve the problems of severe oxidation, many crystal defects, high laser threshold and poor stability, the present invention proposes a two-dimensional tin-based perovskite antioxidant synthesis method based on a dual oxidation inhibition strategy and its application in low-threshold long-life lasers.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A method for preparing an anti-oxidation two-dimensional tin-based perovskite comprises the following steps:

[0006] Step 1: In an oxygen-free environment, organic ammonium salt, SnI2 and electron-donating molecules are added to a mixed solvent of hydroiodic acid and hypophosphorous acid;

[0007] Step 2: heating the obtained mixture in a sealed container until it is completely dissolved, and then crystallizing by an in-situ two-step supersaturated solution cooling method;

[0008] Step 3: Collect single crystals in an inert environment to obtain two-dimensional tin-based perovskite single crystals, which have high quality and can achieve large-scale preparation with a diameter of 4 mm.

[0009] In the above technical solution, further, the requirement for the anaerobic environment is O2 < 5 ppm.

[0010] Further, the electron-donating molecules include but are not limited to biuret, cyanuric acid, thiocyanuric acid, etc.

[0011] Further, the organic ammonium salt is one or more of phenethylammonium (PEAI) and methyl hydrogen iodide (MAI).

[0012] Further, the addition amount of the electron-donating molecule is 50%-100% of the molar amount of SnI2.

[0013] Further, the addition amount of the organic ammonium salt is determined according to the type of tin-based perovskite to be prepared: for (PEA)2SnI4, the molar amount of PEAI is 50% of the molar amount of SnI2; for (PEA)2MASn2I7, the molar amount of PEAI is 43% of the molar amount of SnI2, and the molar amount of MAI is 100% of the molar amount of SnI2; for (PEA)2MA2Sn3I 10 For, the molar amount of PEAI is 43% of the molar amount of SnI2, and the molar amount of MAI is 150% of the molar amount of SnI2.

[0014] Further, the in-situ two-step supersaturated solution cooling crystallization method is specifically as follows: the mixed solution in the sealed container is first cooled from 105 °C to 20 °C at a rate of 0.01-0.02 °C / min; then it is heated to 90-100 °C at a rate of 2-3 °C / min; and then it is cooled to 20 °C at a rate of 0.05-0.07 °C / min.

[0015] Further, the volume ratio of hydroiodic acid to hypophosphorous acid in the mixed solvent is 10:1.

[0016] Application of the obtained two-dimensional tin-based perovskite in a laser: the single crystal is mechanically peeled to obtain a nanosheet, and the nanosheet is directly used to prepare a geometric resonance cavity by focused ion beam etching in an inert environment; then the nanosheet is placed in an 80K low-temperature vacuum chamber and excited by a femtosecond laser to collect laser signals.

[0017] The obtained laser is a low-threshold and long-life laser, and its laser threshold can be lower than 1 μJ / cm 2 , and the laser intensity can be increased by more than 300% under continuous optical pumping.

[0018] The geometric resonance cavity can include a circular array (WGM mode) or a square array (FP mode). In addition, by controlling the side length of the nanosheet, the laser mode number can be changed.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) The double oxidation inhibition strategy adopted in the present invention: By coordinating Sn2+ with an electron-donating molecule (biuret) and the two-step in-situ growth method without oxygen, it can be verified by XPS that the surface content of Sn 4+ can be reduced from >90% (in an air environment) to <10%, and the crystal size can be increased from <1 mm to ~4 mm.

[0021] (2) The present invention successfully achieves an ultra-low laser threshold: The laser threshold of (PEA)2MASn2I7 nanosheets can be as low as 0.88 μJ / cm 2 , which is comparable to that of lead-based perovskites.

[0022] (3) The present invention proves the self-healing property of two-dimensional tin-based perovskites: The laser intensity increases by more than 300% under continuous optical pumping.

[0023] (4) The present invention proves the designability of the cavity: A laser array is realized by focused ion beam etching. Description of the Drawings

[0024] Figure 1 Powder XRD data diagrams of (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 3) prepared by the present invention under different synthesis environments;

[0025] Figure 2 PL data diagrams of (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 3) prepared by the present invention under different synthesis environments;

[0026] Figure 3 Sn content diagrams on the single crystal surface of (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 3) prepared by the present invention under different synthesis environments; 4+ ;

[0027] Figure 4 Statistical graphs of carrier lifetimes of single crystals of (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 3) prepared by the present invention under different synthesis environments;

[0028] Figure 5 (PEA)2MA2Sn3I prepared for the present invention 10 and (PEA)2MA2Pb3I 10 Photostability data graph (excited by the same light source);

[0029] Figure 6 (PEA)2MA prepared for the present invention in the presence of biuret molecules n-1 Sn n I 3n+1 (n = 1 - 3) Single crystal optical pump laser data graph;

[0030] Figure 7 (PEA)2MA prepared for the present invention under different synthesis environments n-1 Sn n I 3n+1 (n = 1 - 3) Single crystal laser threshold statistical distribution graph;

[0031] Figure 8 (PEA)2MA2Sn3I prepared for the present invention 10 and (PEA)2MA2Pb3I 10 Laser stability data graph (excited by the same light source);

[0032] Figure 9 (PEA)2SnI4 circular nanosheet and laser photograph data graph prepared for the present invention;

[0033] Figure 10 (PEA)2SnI4 square nanosheet array and laser photograph data graph prepared for the present invention;

[0034] Figure 11 Electric field distribution data graph of the laser array simulated by COMSOL used in the present invention; Detailed implementation mode

[0035] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. The methods are all conventional methods unless otherwise specified. The raw materials can all be obtained from public commercial channels unless otherwise specified.

[0036] Example: Antioxidant preparation of tin-based perovskite and its application in low-threshold long-life lasers

[0037] 1) Preparation of two-dimensional tin-based perovskite single crystal by antioxidant strategy

[0038] In a glove box filled with nitrogen, the raw materials required for crystal growth were added to a mixed solvent of hydroiodic acid and hypophosphorous acid according to a high-purity single-crystal formula. After sealing, two-dimensional tin-based perovskite single crystals with different n values were obtained by in-situ two-step supersaturated solution cooling crystallization.

[0039] In the examples of the present invention, tin-based perovskite single crystals were prepared under different synthesis environments:

[0040] Example 1

[0041] ((PEA)2MA containing biuret n-1 Sn n I 3n+1 (n = 1 - 3) single crystal preparation):

[0042] For the preparation of (PEA)2SnI4 single crystals, 0.2 mmol of PEAI, 0.4 mmol of SnI2, and 0.2 mmol of biuret were added to a glass bottle containing 2 mL of HI and 0.2 mL of H3PO2. When preparing (PEA)2MASn2I7, 0.17 mmol of PEAI, 0.40 mmol of MAI, 0.40 mmol of SnI2, and 0.2 mmol of biuret were added to a glass bottle containing the same solvent. When preparing (PEA)2MA2Sn3I 10 , 0.17 mmol of PEAI, 0.67 mmol of MAI, 0.44 mmol of SnI2, and 0.2 mmol of biuret were added to a glass bottle containing the same solvent. All operations were carried out in a glove box filled with nitrogen. After the raw materials were completely dissolved, the resulting mixture was heated to complete dissolution in a sealed container, and then cooled from 105 °C to 20 °C at a rate of 0.01 °C / min; then heated to 90 °C at a rate of 2 °C / min; and then cooled to 20 °C at a rate of 0.05 °C / min to finally obtain pure-phase single crystals. When collecting the single crystals, it was necessary to ensure that the oxygen content and water content in the glove box were <5 ppm. Adding H3PO2 could ensure that Sn 4+ was completely reduced to Sn 2+ .

[0043] Example 2 (preparation of (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 3) single crystals) in a nitrogen environment:

[0044] When preparing (PEA)2SnI4 single crystals, 0.2 mmol of PEAI and 0.4 mmol of SnI2 were added to a glass bottle containing 2 mL of HI and 0.2 mL of H3PO2. When preparing (PEA)2MASn2I7, 0.17 mmol of PEAI, 0.40 mmol of MAI, and 0.4 mmol of SnI2 were added. When preparing (PEA)2MA2Sn3I 10 , 0.17 mmol of PEAI, 0.67 mmol of MAI, and 0.4 mmol of SnI2 were added. The single crystal growth and collection process was the same as the biuret single crystal preparation scheme in Example 1 and was completed under a nitrogen protection environment throughout the process.

[0045] Example 3 (preparation of (PEA)2MA n-1 Sn n I 3n+1 (n = 1 - 3) single crystals):

[0046] When preparing (PEA)2SnI4 single crystals, 0.2 mmol of PEAI and 0.4 mmol of SnI2 were added to a glass bottle containing 2 mL of HI and 0.2 mL of H3PO2. When preparing (PEA)2MASn2I7, 0.17 mmol of PEAI, 0.40 mmol of MAI, and 0.4 mmol of SnI2 were added. When preparing (PEA)2MA2Sn3I 10 , 0.17 mmol of PEAI, 0.67 mmol of MAI, and 0.4 mmol of SnI2 were added. The whole process of raw material weighing, solvent addition, and single crystal collection was carried out in an air environment, and other procedures were the same as the biuret single crystal preparation scheme in Example 1.

[0047] Example 4 Comparative sample (PEA)2MA2Pb3I 10 Single crystal preparation:

[0048] When preparing (PEA)2MA2Pb3I 10 single crystals, 0.15 mmol of PEAI, 0.53 mmol of MAI, and 0.59 mmol of PbO were added to a glass bottle containing 0.9 mL of HI and 0.1 mL of H3PO2. The preparation method used the slow cooling method.

[0049] The characterization data comparison of tin - based perovskite single crystals prepared under different synthesis environments is as Figures 1-4 shown; Figure 1 It is proved that the electron - donating molecule (biuret) did not enter the perovskite lattice. Figure 2 It is proved that the fluorescence spectrum of the crystals prepared by the antioxidant strategy has not changed. Figure 3 It is proved that the electron - donating molecule (biuret) has a strong protective effect on tin - based perovskites.Figure 4 It is demonstrated that the electron-donating molecule (biuret) helps to improve the carrier lifetime and crystal quality. Figure 5 (PEA)2MA2Sn3I prepared by the antioxidant method of the present invention 10 and (PEA)2MA2Pb3I 10 The photostability data graph (when testing the photostability and laser stability, keeping the focal plane of the nanosheets consistent and the temperature constant) proves that the obtained two-dimensional tin-based perovskite has excellent photostability.

[0050] 2) Lasers with low threshold and long lifetime

[0051] After mechanically exfoliating large single crystals into nanosheets, they are placed in an 80K vacuum chamber and excited with femtosecond lasers. Figure 6 It is demonstrated that the two-dimensional tin-based perovskite has strong laser emission. Figure 7 It is demonstrated that the two-dimensional tin-based perovskite prepared by the antioxidant strategy has a low laser threshold. Figure 8 It is demonstrated that the two-dimensional tin-based perovskite has an ultra-long laser lifetime.

[0052] 3) Laser cavity design

[0053] Use focused ion beam etching on tin-based perovskite nanosheets to change the laser generation mode. Figure 9 It is the circular nanosheet and laser photograph obtained by etching. Figure 10 It is the square nanosheet array and laser array obtained by etching. Figure 11 It is the electric field distribution of the laser array simulated by COMSOL.

[0054] The above-described embodiments are only some preferred solutions of the present invention, but they are not intended to limit the present invention. Those of ordinary skill in the relevant technical field can still make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by adopting equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. An antioxidant preparation method for two-dimensional tin-based perovskite, characterized in that, It includes the following steps: Step 1: Under an anaerobic environment, add an organic ammonium salt, SnI2, and an electron-donating molecule into a mixed solvent of hydroiodic acid and hypophosphorous acid; Step 2: Heat the obtained mixture in a sealed container until it is completely dissolved, and then crystallize it by an in-situ two-step supersaturated solution cooling method; Step 3: Collect single crystals in an inert environment to obtain two-dimensional tin-based perovskite single crystals.

2. The method according to claim 1, wherein The requirement for the anaerobic environment is O2 < 5 ppm.

3. The method according to claim 1, wherein The electron-donating molecule includes but is not limited to biuret, cyanuric acid, and thiocyanuric acid.

4. The method according to claim 1, wherein The organic ammonium salt is one or more of phenethylammonium (PEAI) and methyl hydroiodide (MAI).

5. The method according to claim 1, characterized in that The addition amount of the electron-donating molecule is 50%-100% of the molar amount of SnI2.

6. The method according to claim 1, wherein The in-situ two-step supersaturated solution cooling method crystallization is specifically as follows: First, cool the mixed solution in the sealed container from 105°C to 20°C at a rate of 0.01-0.02°C / min; then heat it to 90-100°C at a rate of 2-3°C / min; and then cool it to 20°C at a rate of 0.05-0.07°C / min.

7. The method according to claim 1, wherein The volume ratio of hydroiodic acid to hypophosphorous acid in the mixed solvent is 10:

1.

8. A two-dimensional tin-based perovskite single crystal prepared by the method according to any one of claims 1-7.

9. The application of the two-dimensional tin-based perovskite single crystal as described in claim 8 in a laser, characterized in that, Mechanically exfoliate the single crystal to obtain a nanosheet, prepare a geometric resonance cavity by focused ion beam etching in an inert environment; then place the nanosheet in an 80K low-temperature vacuum chamber and use femtosecond laser excitation to collect the laser signal.

10. A laser with a low threshold and long lifespan, characterized in that, Prepared from the two-dimensional tin-based perovskite single crystal as described in claim 8, with a laser threshold lower than 1 μJ / cm 2 , and the laser intensity increases by more than 300% under continuous optical pumping.

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