Preparation and application of Sn (IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cations

Abstract

The invention discloses a preparation method and an application of a Sn (IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cations. The molecular structure general formula of the hybrid perovskite crystal is [C7H16P] 2 [SnBr6], and the molecular weight is 860.48. Wherein [C7H16P] < + > is a (cyclopropylmethyl) trimethylphosphine cation, and [SnBr6] < 2-> octahedron is an inorganic metal framework part. According to the hybrid perovskite crystal, reversible phase change at the room temperature or above occurs once near 322K / 273K and 395K / 375K respectively. The hybrid perovskite crystal is high in stability, the phase change at 395K / 375K can be circulated from a high dielectric state to a low dielectric state for multiple times, and the hybrid perovskite crystal shows a relatively good bistable dielectric response characteristic and has the potential of becoming a dielectric switch environment-friendly material at the room temperature or above.

Description

Technical Field

[0001] The invention relates to a method for preparing an environmentally friendly tin-based hybrid perovskite. The Sn(IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cations has a switchable dielectric response and belongs to the field of hybrid perovskite crystal functional materials. Background Art

[0002] The development of phase change materials has made remarkable progress in the fields of information storage, temperature sensing, energy harvesting, etc. Phase change materials have attracted widespread attention due to their various interesting physical properties. In particular, the switchable physical properties of the material that change in different stable states under external stimuli (such as temperature, pressure, etc.) provide good prospects for practical applications. For example, dielectric switchable materials, in which the dielectric constant changes from a "high" state to a "low" state under the application of temperature stimulation, have potential application value in temperature sensors. At present, there is an urgent need to develop new stable switchable dielectric response materials. However, how to prepare compounds with phase change and good dielectric switching function remains a great challenge.

[0003] Organic-inorganic hybrid perovskite materials are known for their structural diversity. The flexible combination of organic cation parts with inorganic metal frameworks provides many new ideas for the design of phase change materials. The structural modification of organic cations will have an impact on the ordering, orientation or conformation, which is very important for the occurrence of phase transition. However, the cations of the perovskite family are currently mainly limited to monovalent amine cations, and the development of dielectric switching materials is restricted. Since phosphorus atoms and nitrogen atoms belong to the same main group, the corresponding phosphine cations have similar flexibility to amine cations. However, the differences in atomic radius and atomic mass between N and P atoms may lead to differences in structure and properties. The introduction of phosphine-based organic cations provides new ideas for exploring materials with switchable dielectric properties. For example, [(CH 3 ) 3 PCH 2 F]CdCl 2 Br is a hybrid perovskite crystal with a switchable dielectric response based on phosphine cations.

[0004] The inorganic metal part of hybrid perovskites often uses Sb(Ⅲ), Bi(Ⅲ), Pb(Ⅱ), etc., but there are fewer studies based on Sn(Ⅳ). The low-dimensional Sn(Ⅳ) hybrid perovskite inorganic skeleton is scattered, providing sufficient space for the movement of organic cations, which is conducive to the phase change of the material. At the same time, compared with the common hybrid perovskite crystal materials with switchable dielectric response based on Pb(Ⅱ), the Sn(Ⅳ)-based hybrid perovskite material has phase change and stable dielectric switching functions, and its toxicity is lower than that of lead and more environmentally friendly. In summary, the invention of a Sn(Ⅳ)-based hybrid perovskite material containing quaternary phosphonium salt cations with switchable dielectric response and phase change characteristics is extremely important in the preparation and development of dielectric switch materials. Summary of the invention

[0005] Purpose of the invention: The first purpose of the present invention is to provide a Sn(IV)-based hybrid perovskite crystal containing a quaternary phosphonium cation; the second purpose of the present invention is to provide a method for preparing a Sn(IV)-based hybrid perovskite crystal containing a quaternary phosphonium cation; the third purpose of the present invention is to provide an application of a Sn(IV)-based hybrid perovskite crystal containing a quaternary phosphonium cation in the preparation of a dielectric switch material having a phase change above room temperature.

[0006] Technical solution: A Sn(IV)-based hybrid perovskite crystal containing a quaternary phosphonium salt cation, wherein the molecular formula of the hybrid perovskite crystal is [C 7 H 16 P] 2 [SnBr 6 ], with a molecular weight of 860.48, wherein the [C 7 H 16 P] + It is (cyclopropylmethyl)trimethylphosphonium cation.

[0007] A reversible phase transition above room temperature occurred at 322K / 273K and 395K / 375K. At 298K, the hybrid perovskite crystals crystallized in the monoclinic system, P2 1 / nCentrosymmetric space group.

[0008] The unit cell parameters of the hybrid perovskite crystal at 298K include:

[0009]

[0010] The method for preparing the Sn(IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cations comprises the following steps:

[0011] (1) Synthesis of organic cation (cyclopropylmethyl) trimethylphosphine bromide: trimethylphosphine, bromomethylcyclopropane and anhydrous acetonitrile were added to a reaction vessel and stirred thoroughly to obtain [C 7H 16 P]Br;

[0012] (2) preparing a reaction solution: dissolving inorganic tin in a hydrobromic acid solution, stirring thoroughly to obtain a light yellow clear solution; dissolving (cyclopropylmethyl)trimethylphosphine bromide obtained in step (1) in hydrobromic acid, stirring thoroughly to obtain a colorless, transparent, clear solution;

[0013] (3) Synthesis of Sn(IV)-based hybrid perovskite crystals containing quaternary phosphonium cations: The two clarified solutions obtained in step (2) are mixed, stirred thoroughly, and allowed to stand on a constant temperature hot plate to wait for the growth of Sn(IV)-based hybrid perovskite crystals containing quaternary phosphonium cations.

[0014] The mass concentration of the hydrobromic acid solution described in step (2) is 48%.

[0015] The solid-to-liquid ratio of the inorganic tin to the hydrobromic acid solution in step (2) is 1:37-74 g / mL.

[0016] The ratio of the quaternary phosphonium salt cation to the hydrobromic acid solution in step (2) is 1:14-23 g / mL; the molar ratio of the inorganic tin to the quaternary phosphonium salt cation is 1:1.

[0017] The inorganic tin described in step (2) is stannous oxide (SnO).

[0018] The temperature of the constant temperature heating platform described in step (3) is 45°C.

[0019] Beneficial effects:

[0020] 1. The method for preparing (cyclopropylmethyl)trimethylphosphonium bromide provided by the present invention has a short reaction time. Anhydrous acetonitrile is used to replace the toxic and expensive anhydrous tetrahydrofuran commonly used in the synthesis of quaternary phosphonium salt cations. The product is obtained more cheaply, with high yield and good repeatability.

[0021] 2. The present invention provides a method for preparing Sn(IV)-based hybrid perovskite crystals containing quaternary phosphonium salt cations, which uses solvent volatilization at room temperature and is more convenient to operate. The preparation method has a high yield of hybrid perovskite crystals and good repeatability.

[0022] 3. Due to SnBr 4 The purchase price is high, SnO 2 It is difficult to dissolve in common hydrobromic acid solution, which causes inconvenience in operation. Due to these restrictions, the present invention uses SnO, an inorganic tin that is cheap and easy to dissolve in hydrobromic acid, to be oxidized during the dissolution process in hydrobromic acid. Then, organic cations are added to coordinate with it to form Sn(IV)-based hybrid perovskite crystals containing quaternary phosphonium salt cations. This method is simpler, more efficient and cheaper.

[0023] 4. The Sn(IV)-based hybrid perovskite crystals containing quaternary phosphonium salt cations prepared by the present invention exhibit two phase transitions above room temperature. The phase transition at 395K / 375K exhibits a switchable dielectric response, which can be used for the preparation and application of dielectric switch materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The hybrid perovskite crystal prepared in Example 1 [C 7 H 16 P] 2 [SnBr 6 ]Asymmetric unit and stacking structure diagram at 298K;

[0025] Figure 2 The hybrid perovskite crystal prepared in Example 1 [C 7 H 16 P] 2 [SnBr 6 ]PXRD simulation diagram at 298K and experimental test diagrams at 298K and 413K;

[0026] Figure 3 The hybrid perovskite crystal prepared in Example 1 [C 7 H 16 P] 2 [SnBr 6 ]’s DSC curve;

[0027] Figure 4 The hybrid perovskite crystal prepared in Example 1 [C 7 H 16 P] 2 [SnBr 6 ]'s dielectric constant measurement diagram;

[0028] Figure 5 The hybrid perovskite crystal prepared in Example 1 [C 7 H 16 P] 2 [SnBr 6 ] of the dielectric switch. DETAILED DESCRIPTION

[0029] The reagents used in the experiments of the present invention are all commercially purchased analytically pure reagents.

[0030] Instruments used in the experiment:

[0031] The variable temperature single crystal X-ray diffractometer was Rigaku CCD Saturn724;

[0032] The variable temperature powder X-ray diffractometer was a Rigaku SmartL X-ray diffractometer;

[0033] The differential scanning calorimetry (DSC) tester was a Netzsch Model DSC 200F3;

[0034] The dielectric properties test instrument is Tonghui Model TH2828A;

[0035] The software used for crystal structure analysis was Olex2.

[0036] The Sn(IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cations of the present invention comprises a (cyclopropylmethyl)trimethylphosphonium cation, [SnBr 6 ] 2- Inorganic metal skeleton. The stacking structure of the hybrid perovskite crystal is a zero-dimensional structure, and its molecular structure formula is [C 7 H 16 P] 2 [SnBr 6 ], with a molecular weight of 860.48. The hybrid perovskite crystals each undergo a reversible phase transition above room temperature at around 322K / 273K and 395K / 375K. At 298K, the hybrid perovskite crystals belong to the monoclinic system, with a space group of P2 1 / n, centrosymmetric space group.

[0037] Wherein, the unit cell parameters of the hybrid perovskite crystal at 298K include:

[0038]

[0039] The method for preparing a Sn(IV)-based hybrid perovskite crystal containing a quaternary phosphonium salt cation of the present invention comprises the following steps:

[0040] (1) Synthesis of organic cation (cyclopropylmethyl) trimethylphosphine bromide: Add trimethylphosphine, bromomethylcyclopropane, and anhydrous acetonitrile to a reaction vessel, stir the reaction well, and obtain [C 7 H 16 P]Br.

[0041] (2) Synthesis of Sn(IV)-based hybrid perovskite crystals containing quaternary phosphonium salt cations: Dissolve inorganic tin in a beaker containing hydrobromic acid solution, stir thoroughly to dissolve, and obtain a light yellow clear solution. Dissolve (cyclopropylmethyl)trimethylphosphine bromide obtained in step (1) in a beaker containing hydrobromic acid, stir thoroughly to dissolve, and obtain a colorless, transparent, clear solution.

[0042] (3) The two clarified solutions obtained in step (2) are mixed, stirred for 30 minutes, and then placed on a constant temperature hot plate. A Sn(IV)-based hybrid perovskite crystal containing a quaternary phosphonium salt cation can be grown in about 3-4 days.

[0043] Wherein, in step (1), the synthesis step of the organic cation (cyclopropylmethyl)trimethylphosphonium bromide is:

[0044] (a) Add 50-60 mL of anhydrous acetonitrile to a three-necked flask and introduce nitrogen protective gas into the apparatus for 20-30 minutes.

[0045] (b) Using a syringe, 20-23 mmol of bromomethylcyclopropane solution and 20 mmol of trimethylphosphine solution were successively injected into the flask of step (a), and the mixture was reacted in a constant temperature oil bath at 70° C. for 34-40 hours, and a large amount of white powder was finally produced in the flask.

[0046] (c) The product in step (b) is filtered to obtain a colorless clear solution and a white solid powder.

[0047] (d) washing the white solid powder obtained in step (c) with ethyl acetate and drying to obtain a pure white solid powder.

[0048] (e) The white solid powder obtained in step (d) is (cyclopropylmethyl)trimethylphosphonium bromide.

[0049] Wherein, in step (2), the mass concentration of the hydrobromic acid solution is 48%.

[0050] Wherein, in step (2), the solid-to-liquid ratio of the inorganic tin to the hydrobromic acid solution is 1:37-74 g / mL.

[0051] Wherein, in step (2), the solid-to-liquid ratio of the quaternary phosphonium salt cation to the hydrobromic acid solution is 1:14-23 g / mL.

[0052] Wherein, in step (2), the molar ratio of the inorganic tin to the quaternary phosphonium salt cation is 1:1.

[0053] Wherein, in step (3), the temperature of the constant temperature heating platform is 45°C.

[0054] In the present invention, the synthesis mechanism of organic cation (cyclopropylmethyl) trimethylphosphonium bromide is:

[0055]

[0056] The Sn(IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cations described in the present invention has relevant applications in the preparation of dielectric response materials with phase transition above room temperature.

[0057] The Sn(IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cations described in the present invention is a hybrid material that exhibits a dielectric switching function under temperature stimulation.

[0058] Example 1

[0059] Synthesis of organic cation (cyclopropylmethyl) trimethylphosphonium bromide: Add 50mL of anhydrous acetonitrile to a dry, clean three-necked flask, introduce nitrogen protective gas into the device for 30 minutes, and start stirring. Use a syringe to inject 1.74mL of trimethylphosphine into the three-necked flask and stir for 3-5 minutes. Use a syringe to inject 1.8mL of bromomethylcyclopropane into the three-necked flask, stir well for 5 minutes, raise the temperature of the constant temperature oil bath to 70°C, and heat to reflux for 36 hours. Eventually, a white solid powder will be produced inside the flask. The solid-liquid mixture in the flask is filtered to obtain a large amount of white powder solid. The white powder is washed with 20mL of ethyl acetate solution and finally dried. The final product is weighed on a scale, and the calculated final yield is 90.73%.

[0060] Preparation of hybrid perovskite crystals: Weigh 0.135g of stannous oxide powder on a balance and put it into a 50mL beaker 1, add 10mL of hydrobromic acid solution to beaker 1, heat to 50°C, stir to dissolve, and obtain a light yellow clear solution. Weigh 0.211g of (cyclopropylmethyl)trimethylphosphine bromide on a balance and dissolve it in beaker 2 with 4mL of hydrobromic acid, stir to dissolve, and obtain a colorless clear solution. Add the solution in beaker 2 to beaker 1, and continue to stir the mixed solution on a magnetic stirring table at 50°C for 30 minutes to finally obtain a clear yellow solution. Place it on a constant temperature hot table at 45°C to slowly evaporate the solvent. After 3 days, a large number of blocky yellow hybrid perovskite crystals are produced at the bottom of the beaker. The crystals are fished out with a medicine spoon, and the mother liquor remaining on the surface of the crystals is washed with a small amount of distilled water. Dry and weigh, and the resulting hybrid perovskite crystals [C 7 H 16 P] 2 [SnBr 6 ], with a yield of 95.76%.

[0061] The crystals obtained in Example 1 were selected by using a microscope to select single crystals of suitable size, transparency and no cracks. The single crystal X-ray diffraction structure of the selected crystals was measured at 200K, 298K and 343K using a variable temperature single crystal X-ray diffractometer, and the structure was analyzed and refined using Olex2 software. The results showed that the hybrid perovskite crystals obtained in Example 1 at 200K, 298K and 343K were all crystallized in the monoclinic system P2 1 / n space group, so the phase transition at 322K / 273K is the same structure. The asymmetric unit and stacking structure of its crystal structure at 298K are as follows Figure 1 As shown. The PXRD pattern at 298K was tested by a variable temperature powder X-ray diffractometer to verify its purity. The PXRD pattern tested at 413K was compared with the PXRD pattern at 298K. It was found that the main peak of 9.8°-12.6° at 298K was split, the peaks of 15.46° and 18.62°-31.6° disappeared, and some peaks shifted to low angles, proving the occurrence of phase transition at 395K / 375K. The results are shown in Figure 2 The specific data of the crystal structure of the compound are shown in Table 1.

[0062]

[0063]

[0064] The hybrid perovskite crystal obtained in Example 1 was ground, and 10 mg of the crystal powder was weighed and measured using a differential scanning calorimeter (DSC) at N 2 DSC analysis was performed under protection with a heating / cooling rate of 10K / min. Figure 3 It can be seen that in the measurement of the heating-cooling cycle, a pair of endothermic / exothermic peaks above room temperature appeared near 322K / 273K and 395K / 375K, and the peak areas were basically the same, indicating that the Sn(IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cations prepared by the present invention is a material with reversible phase transition characteristics.

[0065] The hybrid perovskite single crystal obtained in Example 1 was ground, and an appropriate amount of crystal powder was weighed for tableting. Conductive silver paste was applied on both sides of the tablet, and the tablet was connected to the electrode base with a copper wire. The dielectric properties were studied using an impedance analyzer. Figure 4 It can be seen that during the heating / cooling cycle, an obvious "step-like" thermal anomaly appeared near 322K / 273K and 395K / 375K, which once again proves that the Sn(IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cations prepared by the present invention is a reversible phase change material, and the phase change at 395K / 375K has a good dielectric response. Figure 5 As shown, during multiple dielectric switch test cycles, it exhibits good stability and no obvious loss occurs, indicating that the hybrid perovskite crystal prepared by the present invention is a potential switchable dielectric switch material.

[0066] Example 2

[0067] Synthesis of organic cation (cyclopropylmethyl) trimethylphosphonium bromide: Add 60mL of anhydrous acetonitrile to a dry, clean three-necked flask, introduce nitrogen protective gas into the device for 30 minutes, and start stirring. Use a syringe to inject 1.74mL of trimethylphosphine into the three-necked flask and stir for 3-5 minutes. Use a syringe to inject 1.9mL of bromomethylcyclopropane into the three-necked flask, stir well for 5 minutes, raise the temperature of the constant temperature oil bath to 70°C, and heat to reflux for 39 hours. Eventually, a white solid powder will be produced inside the flask. The solid-liquid mixture in the flask is filtered to obtain a large amount of white powder solid. The white powder is washed with 20mL of ethyl acetate solution and finally dried. The final product is weighed on a scale, and the calculated final yield is 91.13%.

[0068] Preparation of hybrid perovskite crystals: Weigh 0.135g of stannous oxide powder on a balance and put it into a 50mL beaker 1, add 8mL of hydrobromic acid solution to beaker 1, heat to 50°C, stir to dissolve, and obtain a light yellow clear solution. Weigh 0.2g of (cyclopropylmethyl)trimethylphosphine bromide on a balance and dissolve it in beaker 2 with 3mL of hydrobromic acid, stir to dissolve, and obtain a colorless clear solution. Add the solution in beaker 2 to beaker 1, and continue to stir the mixed solution on a 50°C magnetic stirring table for 30 minutes to finally obtain a clear yellow solution. Place it on a constant temperature hot table at 45°C to slowly evaporate the solvent. After 3-4 days, a large number of blocky yellow hybrid perovskite crystals are produced at the bottom of the beaker. The crystals are fished out with a medicine spoon, and the mother liquor remaining on the surface of the crystals is washed with a small amount of distilled water. Dry and weigh, and the resulting hybrid perovskite crystals [C 7 H 16 P] 2 [SnBr 6 ], with a yield of 95.81%. The results of variable temperature single crystal X-ray diffraction, variable temperature powder X-ray diffraction, differential scanning calorimetry and dielectric properties test on the hybrid perovskite crystal obtained in Example 2 using the instrument in Example 1 are basically consistent with those in Example 1.

[0069] Example 3

[0070] Synthesis of organic cation (cyclopropylmethyl) trimethylphosphonium bromide: Add 50mL of anhydrous acetonitrile to a dry, clean three-necked flask, introduce nitrogen protective gas into the device for 30 minutes, and start stirring. Use a syringe to inject 1.75mL of trimethylphosphine into the three-necked flask and stir for 3-5 minutes. Use a syringe to inject 1.8mL of bromomethylcyclopropane into the three-necked flask, stir well for 5 minutes, raise the temperature of the constant temperature oil bath to 70°C, and heat to reflux for 39 hours. Eventually, a white solid powder will be produced inside the flask. The solid-liquid mixture in the flask is filtered to obtain a large amount of white powder solid. The white powder is washed with 20mL of ethyl acetate solution and finally dried. The final product is weighed on a scale, and the calculated final yield is 90.63%.

[0071] Preparation of hybrid perovskite crystals: Weigh 0.269g of stannous oxide powder on a balance and put it into a 50mL beaker 1, add 19mL of hydrobromic acid solution to beaker 1, heat to 50°C, stir to dissolve, and obtain a light yellow clear solution. Weigh 0.426g of (cyclopropylmethyl)trimethylphosphine bromide on a balance and dissolve it in beaker 2 with 7mL of hydrobromic acid, stir to dissolve, and obtain a colorless clear solution. Add the solution in beaker 2 to beaker 1, and continue to stir the mixed solution on a 50°C magnetic stirring table for 30 minutes to finally obtain a clear yellow solution. Place it on a constant temperature hot table at 45°C to slowly evaporate the solvent. After 4 days, a large number of blocky yellow hybrid perovskite crystals are produced at the bottom of the beaker. The crystals are fished out with a medicine spoon, and the mother liquor remaining on the surface of the crystals is washed with a small amount of distilled water. Dry and weigh, and the resulting hybrid perovskite crystals [C 7 H 16 P] 2 [SnBr 6 ], with a yield of 95.77%. The results of variable temperature single crystal X-ray diffraction, variable temperature powder X-ray diffraction, differential scanning calorimetry and dielectric properties test on the hybrid perovskite crystal obtained in Example 3 using the instruments in Example 1 and Example 2 are basically consistent with those in Example 1 and Example 2.

Claims

1. A Sn(IV)-based hybrid perovskite crystal containing a quaternary phosphonium salt cation, characterized in that: The molecular formula of the hybrid perovskite crystal is [C7H 16 P]2[SnBr6], molecular weight 860.48, wherein the [C7H 16 P] + It is (cyclopropylmethyl)trimethylphosphonium cation.

2. The Sn(IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cation according to claim 1, characterized in that: A reversible phase transition above room temperature occurred near 322K / 273K and 395K / 375K. At 298K, the hybrid perovskite crystals crystallized in the monoclinic system with a P21 / n centrosymmetric space group.

3. The Sn(IV)-based hybrid perovskite crystal containing quaternary phosphonium salt cation according to claim 1, characterized in that: The unit cell parameters of the hybrid perovskite crystal at 298K include:

4. A method for preparing a Sn(IV)-based hybrid perovskite crystal containing a quaternary phosphonium salt cation according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Synthesis of organic cation (cyclopropylmethyl) trimethylphosphine bromide: trimethylphosphine, bromomethylcyclopropane and anhydrous acetonitrile were added to a reaction vessel and stirred thoroughly to obtain [C7H 16 P]Br; (2) preparing a reaction solution: dissolving inorganic tin in a hydrobromic acid solution, stirring thoroughly to obtain a light yellow clear solution; dissolving (cyclopropylmethyl)trimethylphosphine bromide obtained in step (1) in hydrobromic acid, stirring thoroughly to obtain a colorless, transparent, clear solution; (3) Synthesis of Sn(IV)-based hybrid perovskite crystals containing quaternary phosphonium cations: The two clarified solutions obtained in step (2) are mixed, stirred thoroughly, and allowed to stand on a constant temperature hot plate to wait for the growth of Sn(IV)-based hybrid perovskite crystals containing quaternary phosphonium cations.

5. The preparation method according to claim 4, characterized in that: The mass concentration of the hydrobromic acid solution described in step (2) is 48%.

6. The preparation method according to claim 4, characterized in that: The solid-to-liquid ratio of the inorganic tin to the hydrobromic acid solution in step (2) is 1:37-74 g / mL.

7. The preparation method according to claim 4, characterized in that: The ratio of the quaternary phosphonium salt cation to the hydrobromic acid solution in step (2) is 1:14-23 g / mL; the molar ratio of the inorganic tin to the quaternary phosphonium salt cation is 1:

1.

8. The preparation method according to claim 4, characterized in that: The inorganic tin described in step (2) is stannous oxide.

9. The preparation method according to claim 4, characterized in that: The temperature of the constant temperature heating platform described in step (3) is 45°C.

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