Liquid-phase processing medium for halide perovskite and application of liquid-phase processing medium

Abstract

The invention discloses a liquid-phase processing medium for halide perovskite and application thereof, the liquid-phase processing medium comprises a homogeneous solution formed by mixing a solvent and a salt, the solvent is water or alcohol, the chemical structural formula of the salt is CXn, C is selected from monovalent, divalent or trivalent organic or inorganic cations, X is selected from halogen of I, Br, F or Cl, and n is equal to 1, 2 or 3. According to the system, the perovskite is dissolved by utilizing the electrostatic shielding effect in the high-salt electrolyte, and a strong coordination solvent or molecules are not needed to dissolve the perovskite. The perovskite prepared by the method has high crystal quality, so that the degradation of the perovskite material caused by defects or grain boundaries is reduced, and the stability of a device is enhanced; in addition, the defect concentration is low, the carrier capturing or scattering probability is low, the carrier transmission performance can be improved, and therefore the device performance is improved. The method has the advantages of simple and easily available raw materials, simple operation, safety, environmental protection and low cost, and is more suitable for industrial application.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic materials, and particularly to a liquid-phase processing medium for halide perovskites and its applications. Background Art

[0002] Perovskite materials exhibit a series of excellent properties. Among them, halide perovskite materials ABX3 (X = I, Br, Cl) have excellent transport properties, such as a high light absorption coefficient, a high carrier mobility, a long diffusion length for balancing electrons and holes, etc. Halide perovskites are a new type of semiconductor optoelectronic materials, and have been proven to have great prospects in the fields of solar cells, photodetectors, light-emitting diodes, nuclear radiation detectors, etc. Compared with traditional semiconductors, the technical advantage of halide perovskites is that they can be processed in liquid phase, taking into account high quality and low cost, and are expected to develop some new semiconductor processing processes close to room temperature, breaking through the original semiconductor process limitations and obtaining more excellent semiconductor optoelectronic devices.

[0003] Perovskite materials are generally prepared by solution methods. However, the current liquid-phase processing media for perovskites are mainly some solvents with strong coordination abilities to dissolve the key component, lead ions, in perovskite materials. For example, the invention patent CN116669517A discloses a perovskite precursor solution containing pyridine-based additives, a perovskite solar cell, its preparation method, and application. The nitrogen atom in the pyridine-based additive is an electron-donating part, which can form strong coordination with lead in the perovskite material during the crystallization process of the perovskite material, resulting in large-sized perovskite grains. However, the use of these strong coordination solvents may cause problems such as environmental pollution, health threats, and fire hazards in industry on the one hand. On the other hand, the coordination effects involving strong coordination solvents have been proven to possibly lead to crystal defects in perovskite materials, limiting the performance of perovskite optoelectronic devices. Based on this, it is very important to develop a new liquid-phase system for perovskite processing. Although new solvents or additives are constantly being proposed. For example, the invention patent CN117089916A discloses a method for growing perovskite single crystals at low temperature, perovskite single crystals, and detectors. AX and BX2 are added to γ-hydroxybutyric acid lactone (GBL), N,N-dimethylformamide (DMF), or dimethyl sulfoxide (DMSO) according to a ratio of 1:1 to obtain a precursor solution that can be used to grow ABX3 perovskite single crystals. The auxiliary solvent is placed above the precursor solution, and after keeping it at 20 - 60 °C for a period of time, it is placed in a constant-temperature container for nucleation and growth to obtain ABX3 perovskite single crystals. The invention patent CN106611819A discloses a method for inducing the growth of the micro-nano structure interface of an organometallic halide perovskite film for solar cell applications. The metal halide is dissolved in dimethylformamide, and a strong coordination solvent with a molar ratio of 1:1 - 1:2 to the metal halide is added, and it is stirred at 60 °C to obtain a clear and transparent metal halide precursor solution. However, the solvents DMF, DMSO, or 2-ME used in the above methods are also based on the basic principle of dissolving perovskite through coordination effects, resulting in the above problems related to strong coordination solvents still existing. Summary of the Invention

[0004] Aiming at the deficiencies of the above-mentioned prior art, the technical problem to be solved by the present invention is: how to provide a liquid-phase processing medium for halide perovskites and its application to solve the problems such as crystal defects in perovskites obtained by the existing solution method and environmental pollution and insecurity caused by strong coordination solvents or additives.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions: A liquid-phase processing medium for halide perovskite, the chemical structural formula of the halide perovskite being ABX3, where A is selected from organic or inorganic cations of methylamine (MA), formamidine (FA), aziridine (AzrH) or cesium (Cs), B is Pb or Sn, and X is a halogen selected from I, Br, F or Cl; the liquid-phase processing medium comprises a homogeneous solution (a clear and transparent liquid) formed by mixing a solvent and a salt, the solvent being water or alcohol, and the chemical structural formula of the salt being CX n , where C is selected from monovalent, divalent or trivalent organic or inorganic cations, X is a halogen selected from I, Br, F or Cl, and n = 1, 2 or 3.

[0006] Preferably, the alcohol is a unit alcohol or a polyol. Further, the unit alcohol may be selected from methanol, ethanol, propanol, butanol, octanol or pentanol, and the polyol is ethylene glycol, propylene glycol, glycerol, butanediol, octanediol or pentanediol.

[0007] Preferably, the halogen in the salt is the same as the halogen in the halide perovskite. Specifically, for methylammonium lead iodide perovskite (MAPbI3), a salt containing iodide ions is selected, such as sodium iodide (NaI), potassium iodide (KI), methylammonium iodide (MAI), etc. If it is cesium lead bromide perovskite (CsPbBr3), then a salt containing bromide ions is selected, such as lithium bromide (LiBr), cesium bromide (CsBr), methylammonium bromide (MABr), etc. If it is methylammonium lead chloride perovskite (MAPbCl3), then a salt containing chloride ions is selected, such as lithium chloride (LiCl), methylammonium chloride (MACl), etc.

[0008] Preferably, the mass ratio of the salt to the solvent is 0.5 - 3:1; the concentration of the salt in the liquid-phase processing medium is 0.5 - 15 mol / L. Only when the content of the salt reaches this range can a sufficiently high ion concentration be obtained in the liquid phase, so as to fully dissolve the perovskite by utilizing the electrostatic shielding effect of the high ion concentration, and it is possible to make its solubility in the perovskite reach or exceed 0.1 mol / L. However, if the mass of the salt is too high, it cannot be fully dissolved by water or alcohol, that is, a homogeneous liquid cannot be obtained at room temperature or near room temperature.

[0009] Another object of the present invention also lies in providing the application of the above liquid-phase processing medium in the dissolution, crystallization, film deposition, purification or recovery of halide perovskite materials.

[0010] Another object of the present invention also lies in providing a preparation method of halide perovskite, comprising the following steps:

[0011] 1) Place the perovskite raw materials AX and BX2 in the above-mentioned liquid-phase processing medium, stir at room temperature until completely dissolved to form a solution, where A is selected from organic or inorganic cations of MA, FA, AzrH or Cs, B is Pb or Sn, and X is a halogen selected from I, Br, F or Cl;

[0012] 2) Operate the solution obtained in step 1) by heating, cooling or dilution crystallization method to obtain the halide perovskite. Among them, if the cation of the salt in the liquid-phase processing medium is also the cation of the perovskite component (FA, MA, Cs, etc.), the perovskite can be obtained from the liquid-phase processing medium dissolved with the perovskite raw materials by heating. If the cation of the salt in the liquid-phase processing medium is not the cation of the perovskite component (Li, Na, K, Ca, Mg, etc.), the perovskite can be obtained by cooling. Diluting the liquid-phase processing medium with water or alcohol, regardless of its specific components, the perovskite can be obtained from the liquid-phase processing medium dissolved with the perovskite raw materials.

[0013] Preferably, the molar ratio of AX to BX2 is 1-2:1; the concentration of the perovskite raw materials in the liquid-phase processing medium is 0.01-2 mol / L.

[0014] Preferably, the temperature for heating is 30-150 °C, and the temperature for cooling is 0-120 °C; where the cooling or heating is relative to the temperature of preparing the solution, and the temperature of preparing the solution may be any temperature between room temperature and 150 °C. The dilution is achieved by the diffusion of water vapor or alcohol vapor into the solution to dilute the salt concentration.

[0015] Another object of the present invention also lies in providing the halide perovskite prepared by the above method. According to the degree of crystallization or different morphologies, the morphology of the halide perovskite can be one of single crystal, polycrystal, thin film, thick film or nanocrystal.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention proposes a completely new liquid-phase processing system for preparing halide perovskite by solution method. This system uses the electrostatic shielding effect in high-salt electrolyte to dissolve perovskite, without the need for strong coordination solvents or molecules to dissolve perovskite. The perovskite prepared by the present invention has high crystal quality, thereby reducing the degradation of perovskite materials caused by defects or grain boundaries, and enhancing the stability of the device; in addition, the defect concentration is low, the probability of carrier capture or scattering is low, which can improve the carrier transport performance, thereby improving the device performance. The present invention provides new options and ideas for the research of preparing high-performance halide perovskite, which is of great significance.

[0018] 2. The liquid-phase processing system of the present invention uses only water or alcohol as the solvent and common halides such as sodium chloride as the salt. The raw materials are simple, easy to obtain, safe, environmentally friendly, and low in cost, making it more suitable for industrial applications. At the same time, it also solves the problems of existing strong coordination solvents in terms of environmental protection, toxicity, safety, etc. Moreover, this liquid-phase processing system can also be used for the purification of perovskite raw materials and the recycling and treatment of waste perovskite optoelectronic materials and devices such as perovskite photovoltaic panels, showing good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a micrograph of a perovskite single crystal prepared by the present invention.

[0020] Figure 2 It is the carrier transport performance of the perovskite single crystal prepared by the present invention.

[0021] Figure 3 It is for recycling and purifying perovskite waste; A is a schematic diagram of the purification process, B is a comparison of impurity concentrations before and after purification, and C is a physical diagram before and after purification. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] I. A preparation method of halide perovskite

[0024] Example 1: The following steps are adopted in this example:

[0025] 1) Mix MACl salt and water in a mass ratio of 1.54:1 and stir well to obtain a clear and transparent liquid, namely the liquid-phase processing medium, where the concentration of MACl salt reaches 10.4 mol / L.

[0026] 2) Mix perovskite raw materials MACl and PbCl2 in a molar ratio of 1:1, and then place them in the liquid-phase processing medium of step 1), dissolve them fully at room temperature to form a solution, and make the concentration of perovskite raw materials 0.27 mol / L.

[0027] 3) Place the solution obtained in step 2) in an oven and keep it at 50 °C to obtain MAPbCl3 perovskite crystals.

[0028] Example 2: The following steps are adopted in this example:

[0029] 1) Mix MABr salt and water in a mass ratio of 1.87:1 and stir well to obtain a clear and transparent liquid, namely the liquid-phase processing medium, where the concentration of MABr salt reaches 8.3 mol / L.

[0030] 2) Mix the perovskite raw materials MABr and PbBr2 in a molar ratio of 1:1, and then place them in the liquid-phase processing medium of step 1). Dissolve them fully at room temperature to form a solution, and make the concentration of the perovskite raw materials 0.3 mol / L.

[0031] 3) Place the solution obtained in step 2) in an oven, maintain at 38 °C, and at the same time allow water vapor to diffuse into the solution to dilute the salt concentration and accelerate the crystallization of perovskite, then the crystallization of MAPbBr3 perovskite can be obtained.

[0032] Example 3: The following steps are adopted in this example:

[0033] 1) Mix the MAI salt and water in a mass ratio of 1.64:1, stir well, and obtain a clear and transparent liquid, namely the liquid-phase processing medium, where the concentration of the MAI salt reaches 6.4 mol / L.

[0034] 2) Mix the perovskite raw materials MAI and PbI2 in a molar ratio of 1:1, and then place them in the liquid-phase processing medium of step 1). Dissolve them fully at 50 °C to form a solution, and make the concentration of the perovskite raw materials 0.39 mol / L.

[0035] 3) Place the solution obtained in step 2) in an oven, maintain at 50 °C, and at the same time keep the continuous diffusion of ethanol vapor into the solution to dilute the salt concentration, then the crystallization of MAPbI3 perovskite can be obtained.

[0036] Example 4: The following steps are adopted in this example:

[0037] 1) Mix the LiBr salt and water in a mass ratio of 1.11:1, stir well, and obtain a clear and transparent liquid, namely the liquid-phase processing medium, where the concentration of the LiBr salt reaches 6.4 mol / L.

[0038] 2) Mix the perovskite raw materials CsBr and PbBr2 in a molar ratio of 1:1, and then place them in the liquid-phase processing medium of step 1). Dissolve them fully at room temperature to form a solution, and make the concentration of the perovskite raw materials 0.12 mol / L.

[0039] 3) Place the solution obtained in step 2) in an oven, maintain at 25 °C, and at the same time ethanol vapor diffuses into the solution to dilute the salt concentration, then the crystallization of CsPbBr3 perovskite can be obtained.

[0040] Example 5: The following steps are adopted in this example:

[0041] 1) Mix the MAI salt and propylene glycol in a mass ratio of 0.71:1, stir well, and obtain a clear and transparent liquid, namely the liquid-phase processing medium, where the concentration of the MAI salt reaches 3.8 mol / L.

[0042] 2) Mix the perovskite raw materials MAI and PbI2 in a molar ratio of 1:1, and then place them in the liquid-phase processing medium of step 1), fully dissolve them at room temperature to form a solution, and make the concentration of the perovskite raw materials 0.2 mol / L.

[0043] 3) Place the solution obtained in step 2) in an oven and maintain at 50 °C to obtain the crystallization of MAPbI3 perovskite.

[0044] Comparative Example 1: In this comparative example, the conventional solvents DMF + DMSO are used to replace the liquid-phase processing medium, and other steps are the same as in Example 1.

[0045] Comparative Example 2: In this comparative example, the conventional solvent DMF is used to replace the liquid-phase processing medium, and other steps are the same as in Example 2.

[0046] Comparative Example 3: In this comparative example, the conventional solvent 2-ME is used to replace the liquid-phase processing medium, and other steps are the same as in Example 3.

[0047] Comparative Example 4: In this comparative example, the conventional solvent DMSO is used to replace the liquid-phase processing medium, and other steps are the same as in Example 4.

[0048] II. Performance Verification

[0049] 1. Observe the morphology of the perovskites prepared in Examples 1-4 and Comparative Examples 1-4 under a transmission electron microscope, and the results are as Figure 1 shown.

[0050] It can be seen from Figure 1 that compared with the perovskites prepared using conventional solvents (comparative examples), the crystals of the perovskites prepared by the present invention are more transparent and defect-free, with higher crystal quality, thereby reducing the degradation of the perovskite material caused by defects or grain boundaries, and thus enhancing the stability of the device.

[0051] 2. Detect the carrier mobility, mobility-lifetime product, and resistivity of Comparative Examples 2-3 and Examples 2-3 respectively, and the results are as Figure 2 shown.

[0052] It can be seen from Figure 2 that compared with Comparative Examples 2-3, the carrier transport properties of the perovskites obtained by Examples 2-3 using a high-salt electrolyte, including the mobilities of electrons and holes (μ h and μ e ), mobility-lifetime products (μ h ×τ h and μ e ×τ e), and there is a significant increase in the resistivity (ρ), both exceeding an order of magnitude, showing better carrier transport performance, thus reducing transmission losses, improving device performance, and being more conducive to the development of optoelectronic devices such as high-performance and high-stability perovskite solar cells, photodetectors, ray detectors, and light-emitting diodes.

[0053] 3. Place the waste perovskite optoelectronic material in a liquid-phase processing medium (MAI salt and propylene glycol in a mass ratio of 0.71:1) with a MAI salt concentration of 3.8 mol / L, fully dissolve it at room temperature to form a solution, and then place the solution in an oven at 50 °C to recover the perovskite material. See Figure 3 A for details. Use inductively coupled plasma trace element analysis technology to determine the impurities in the perovskite material before and after recovery and purification. The results are as Figure 3 shown in B.

[0054] From Figure 3 B, it can be seen that compared with before recovery and purification, the concentrations of the main impurities such as Na, K, and Ca in the perovskite material after recovery and purification have significantly decreased and can be reduced to the ppm level.

[0055] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A liquid-phase processing medium for halide perovskites, characterized in that, The chemical structural formula of the halide perovskite is ABX3, where A is selected from organic or inorganic cations of MA, FA, AzrH or Cs, B is Pb or Sn, and X is a halogen selected from I, Br, F or Cl; the liquid-phase processing medium includes a homogeneous solution formed by mixing a solvent and a salt, the solvent is water or alcohol, and the chemical structural formula of the salt is CX n , where C is selected from organic or inorganic cations of monovalent, divalent or trivalent, X is a halogen selected from I, Br, F or Cl, and n = 1, 2 or 3.

2. The liquid-phase processing medium for halide perovskites according to claim 1, wherein The alcohol is a monoalcohol or a polyalcohol.

3. The liquid-phase processing medium for halide perovskite according to claim 2, characterized in that, The monoalcohol may be selected from methanol, ethanol, propanol, butanol, octanol or pentanol, and the polyalcohol is ethylene glycol, propylene glycol, glycerol, butanediol, octanediol or pentanediol.

4. The liquid-phase processing medium for halide perovskite according to claim 1, wherein, The halogen in the salt is the same as the halogen in the halide perovskite.

5. The liquid-phase processing medium for halide perovskite according to claim 1, wherein, The mass ratio of the salt to the solvent is 0.5-3:1; the concentration of the salt in the liquid-phase processing medium is 0.5-15 mol / L.

6. Use of the liquid-phase processing medium according to any one of claims 1-5 in the dissolution, crystallization, film deposition, purification or recovery of halide perovskite materials.

7. A method for preparing a halide perovskite, characterized in that, Comprising the following steps: 1) Placing the perovskite raw materials AX and BX2 in the liquid-phase processing medium according to any one of claims 1-5, and stirring at room temperature to 150 °C until completely dissolved to form a solution, wherein A is an organic or inorganic cation selected from MA, FA, AzrH or Cs, B is Pb or Sn, and X is a halogen selected from I, Br, F or Cl; 2) Operating the solution obtained in step 1) by heating, cooling or dilution crystallization method to obtain the halide perovskite.

8. The preparation method of the halide perovskite according to claim 7, characterized in that, The molar ratio of AX to BX2 is 1-2:1; the concentration of the perovskite raw materials in the liquid-phase processing medium is 0.01-2 mol / L.

9. The preparation method of the halide perovskite according to claim 7, characterized in that, The temperature for heating is 30-150 °C, and the temperature for cooling is 0-120 °C; the dilution is by diffusion of water vapor or alcohol vapor into the solution to dilute the salt concentration.

10. A halide perovskite prepared by the method according to any one of claims 7-9, wherein the morphology of the halide perovskite is one of single crystal, polycrystal, thin film, thick film or nanocrystal.

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