Preparation method and application of two-dimensional metal halide perovskite

Abstract

The invention belongs to the technical field of semiconductor photoelectric materials, and relates to a preparation method and application of two-dimensional metal halide perovskite, the chemical formula of the two-dimensional metal halide perovskite is A2BX4, A is positive monovalent amine ions, and B is one or more of Pb < 2 + >, Sn < 2 + > and Ge < 2 + >; x is one or more of Cl <->, I <-> and Br <->; the preparation method comprises the following steps: dissolving BX2 in trioctylphosphine or trioctylphosphine oxide to form a complex solution, and reacting the complex solution with an amine solution corresponding to A-site cations at room temperature to generate A2BX4. According to the method, the one-step synthesis of the two-dimensional perovskite at room temperature is realized, the use of some strong corrosive solvents is avoided, the size of the perovskite can be precisely regulated in a wide range, and the perovskite can be further processed into ink or slurry, so that a large-area and uniform two-dimensional perovskite thin film can be prepared through spraying, printing and other processes; and great convenience is provided for construction of large-area photoelectric devices and promotion of industrial development of the large-area photoelectric devices.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor optoelectronic materials technology, and specifically relates to a method for preparing and applying two-dimensional metal halide perovskites. Background Technology

[0002] Two-dimensional perovskites, as structural derivatives of three-dimensional perovskites, possess quantum confinement effects and significantly higher exciton binding energies, resulting in flexible and tunable band structures and higher radiative recombination efficiency. Their two-dimensional layered structure enables high carrier mobility through transport within the inorganic layers, while simultaneously suppressing halide ion migration, reducing dark current and hysteresis effects. The hydrophobic barrier formed by long-chain organic cations enhances the stability of two-dimensional perovskites. With these unique layered quantum well structures and tunable physicochemical properties, two-dimensional perovskite materials exhibit significant advantages in optoelectronic applications.

[0003] Currently, the main methods for preparing two-dimensional perovskites include vapor deposition and solution spin coating. The former involves expensive equipment and slow deposition rates, making mass production difficult. The latter involves adding amine halides (AX) and metal halides (BX2) to a polar solvent (N,N-dimethylformamide, dimethyl sulfoxide, etc.) in a certain proportion, followed by magnetic stirring for several hours to form a precursor solution. This precursor solution is then spin-coated onto a substrate and subjected to thermal annealing. Although this method is lower in cost, it is not suitable for large-area preparation and results in uneven thickness. Therefore, developing a low-cost, high-quality, and mass-producible method for preparing two-dimensional perovskites is of great scientific and technological significance. Summary of the Invention

[0004] The main objective of this invention is to overcome the deficiencies in the prior art and provide a method for preparing and applying two-dimensional metal halide perovskites. To achieve the above objective, the specific technical solution is as follows: This invention also provides a method for preparing the above-mentioned two-dimensional metal halide perovskite, wherein the chemical formula of the two-dimensional metal halide perovskite is A₂BX₄, wherein A is a monovalent amine ion and B is Pb. 2+ Sn 2+ 、Ge 2+ One or more of them; X is Cl - I - ,Br - One or more of the following; The preparation method is as follows: BX2 is dissolved in trioctylphosphine (TOP) or trioctylphosphine oxide (TOPO) to form a complex solution (represented as TOP-BX2 or TOPO-BX2), and then reacted with an amine solution corresponding to the A-site cation at room temperature to generate A2BX4.

[0005] The two-dimensional metal halide perovskite prepared by the method of this invention is a nanosheet or cluster with a two-dimensional layered perovskite crystal structure. The chemical reaction mechanism is that the amine corresponding to the A-site cation directly abstracts BX2 from the TOP-BX2 or TOPO-BX2 complex to generate A2BX4 with a two-dimensional layered crystal structure. This is a method that can directly synthesize two-dimensional metal halide perovskites in one step at room temperature. The method is simple to operate and can be directly scaled up to meet mass production needs.

[0006] The trioctylphosphine or trioctylphosphine oxide solvent selected in this invention is itself a Lewis base and has suitable coordination ability, which can dissolve metal halide BX2 without directly protonating BX2 to B. 2+ and I - Instead of ions, they form TOP-BX2 or TOPO-BX2 complexes; at the same time, trioctylphosphine or trioctylphosphine oxide does not react chemically with organic amines that are also Lewis bases, thus avoiding the generation of impurity phases during the preparation of two-dimensional perovskites; furthermore, thanks to the coordination of the lone pair electrons of P in trioctylphosphine or trioctylphosphine oxide, it can be adsorbed on the surface of two-dimensional perovskites to maintain the dispersion stability of two-dimensional perovskites and inhibit the aggregation between two-dimensional perovskites.

[0007] Furthermore, the monovalent amine ion is an alkylamine ion containing 4 to 24 carbons (C n H 2n+1 NH3 + (n=4~24), oleylamine ions (C 18 H 35 NH3 + ), phenylethylamine ions (C6H5(CH2)2NH3) + abbreviated as PEA + ) or thiophene ethylamine ion C4H2S-(CH2)2NH3 + abbreviated as TEA +） One of them.

[0008] The monovalent amine ions selected in this invention possess advantages such as high size matching, electronic structure suitable for various optoelectronic devices, and high stability of the perovskite crystal structure. This invention directly selects amines corresponding to the A-site cations to prepare the two-dimensional perovskite A2BX4, which has a significant advantage in ensuring the purity of the reaction products. For example, if PEAI and SnI2 are used as raw materials dissolved in trioctylphosphine as a precursor to prepare the two-dimensional perovskite (PEA)2SnI4, when oleylamine (OAm) is added to participate in the preparation reaction, OAM can also react directly with SnI2 to form the two-dimensional perovskite (OAm)2SnI4, resulting in the appearance of impurity phases in the reaction system. Furthermore, based on the chemical reaction mechanism and the characteristics of the two-dimensional perovskite crystal structure, it can be reasonably inferred that (PEA,OAm)2SnI4, where the A-site ion simultaneously contains PEA, can be formed. + and OAM + Two-dimensional perovskites. For example, if the above OAm is replaced with methylamine (MA), which has a shorter carbon chain, an A-site cation containing PEA is generated. + and MA + Two-dimensional / three-dimensional miscible perovskite structures even generate A-site cations containing only MA + Three-dimensional MASnI3 perovskite impurities.

[0009] Furthermore, the molar ratio of trioctylphosphine or trioctylphosphine oxide to BX2 is not less than 1:1; preferably 1 to 2:1.

[0010] The role of the trioctylphosphine or trioctylphosphine oxide solvent in this invention is to dissolve BX2 and combine it to form unprotonated complexes TOP-BX2 or TOPO-BX2. To ensure that BX2 can be completely dissolved in the trioctylphosphine or trioctylphosphine oxide solvent, its molar ratio with BX2 should not be less than 1:1. The molar ratio of trioctylphosphine or trioctylphosphine oxide solvent to BX2 also affects the quality of the prepared two-dimensional perovskite. When the molar ratio reaches or exceeds 2:1, the quality of the synthesized two-dimensional perovskite begins to decrease. Therefore, the preferred molar ratio of trioctylphosphine or trioctylphosphine oxide to BX2 is 1:1 to 2:1.

[0011] The solubility of BX2 in TOP and TOPO varies depending on the chemical reactivity of elements B and X. Specifically, GX2 (GeI2, GeBr2, GeCl2) dissolves directly in TOP solvent at room temperature with stirring. SnX2 and PbX2 are difficult to dissolve directly in TOP or TOPO solvents at room temperature; however, sufficient dissolution can be achieved by increasing the temperature and extending the stirring time. For example, SnI2 can completely dissolve after continuous stirring at 90°C for about 30 minutes; PbI2 requires continuous stirring at 90°C for about 7 days to completely dissolve in TOP, while PbI2 can completely dissolve in TOPO after stirring at 50°C for about 5 minutes.

[0012] Furthermore, the B-site metal ion in BX2 contains Sn. 2+ 、Ge 2+ One of the solvents used is trioctylphosphine for BX2; the B-site metal ion in BX2 contains only Pb. 2+ When PbX2 is selected, trioctylphosphine or trioctylphosphine oxide solvent is used, with trioctylphosphine oxide solvent being preferred for PbX2.

[0013] Because TOPO has oxidizing properties, it will directly oxidize Sn. 2+ and Ge 2+ Oxidized to Sn 2+ and Ge 4+ The inability to form two-dimensional perovskites is due to the lack of oxidation, so TOP solvent is preferred for the preparation of Sn and Ge-based two-dimensional perovskites. PbX2 is not easily oxidized and is more soluble in TOPO than in TOP. Therefore, TOPO solvent is preferred for the preparation of Pb-based two-dimensional perovskites.

[0014] Furthermore, the molar ratio of BX2 to the amine corresponding to the A-site cation is 1:1 to 30:1, preferably 1:1 to 20:1.

[0015] The amine corresponding to the A-site cation in this invention not only participates in the reaction as a raw material for the A-site ion in A2BX4, but also acts as a ligand adsorbed on the surface of A2BX4 in the form of chemical bonds, so that the size of the prepared A2BX4 can be either a large-sized (50nm~20μm) nanosheet or a small-sized (2~50nm) "magic number cluster".

[0016] The lower the proportion of amine corresponding to the A-site cation, the easier it is to generate small-sized two-dimensional perovskites. For example, when the molar ratio of BX2 to amine is in the range of 10 to 20:1, the average size of the generated two-dimensional perovskite is between 2 nm and 20 nm; when the molar ratio of BX2 to amine is in the range of 1 to 5:1, the average size of the generated two-dimensional perovskite reaches 50 nm to 20 μm. The present invention can flexibly control the size of the two-dimensional perovskite by changing the molar ratio of BX2 to amine according to the specific device application requirements.

[0017] Furthermore, the BX2 concentration is not less than 0.001 mmol / mL, preferably 0.005~0.1 mmol / mL, and more preferably 0.01~0.05 mmol / mL.

[0018] The concentrations of reactant BX2 and the amine corresponding to the A-site cation in the N solvent must be appropriate; if the concentration is too low, the two-dimensional perovskite will not be formed.

[0019] Further, the solvent for the amine solution corresponding to the A-site cation is an N-solvent, which is one or more of a non-polar solvent and a polar solvent; the non-polar solvent is a liquid alkane containing 5 to 16 carbon atoms, toluene, octadecene, etc.; the polar solvent is ethyl acetate, methyl acetate, deionized water, dichloromethane, chloroform, isopropanol, n-butanol, ethanol, acetone, methanol, etc.; preferably, the liquid alkane is one or more of hexane, octane, and pentane.

[0020] The polarity of the nitrogen solvent plays a crucial role in the formation and chemical stability of two-dimensional A₂BX₄ perovskites. The type of nitrogen solvent depends on the reactivity of BX₂; higher reactivity necessitates a lower polarity of the selected nitrogen solvent. This is related not only to the dielectric environment required for the crystallization of two-dimensional perovskites but also to the chemical stability of the two-dimensional perovskite material in solvents with varying polarities. When the X element is fixed, the nitrogen ions are ordered by reactivity at the B-site as follows: Ge 2+ >Sn 2+ >Pb 2+ When element B is fixed, the halide ions at the X site are ranked by reactivity as follows: I - >Br - >Cl - Therefore, the N solvent component may be composed entirely of nonpolar solvents or it may be composed of nonpolar solvents and one or more solvents of different polarities mixed in a certain proportion to modulate its polarity. The polarity of the N solvent needs to be specifically modulated in conjunction with the composition of the B-site metal ions so that TOP-BX2 or TOPO-BX2 can dissolve in the N solvent.

[0021] The specific selection options are as follows: Specifically, for two-dimensional Sn-based halide perovskites: when preparing A₂SnI₄, the N solvent is octadecene or a liquid alkane containing 5-16 carbon atoms; for preparing A₂SnBr₄, A₂SnCl₄, and A₂SnBr₄... y Cl 4-y When preparing A₂SnI, pure toluene was used as the solvent. y Br 4-y 、 A2SnI y Cl 4-y In this case, solvent N is a mixed solvent consisting of toluene and liquid alkane containing 5-16 carbon atoms in a certain proportion, the specific proportion of which is determined by [the specific solvent is determined by the solvent is determined by the solvent is not specified in the original text]. y The value is determined, for example, experimental research has found that when y When the concentration is 0.5, the volume ratio of toluene to liquid alkanes can be approximately 1:1. y The range of values ​​is 0 < y< 4.

[0022] Specifically, for two-dimensional Pb-based halide perovskites: when preparing A2PbI4, pure toluene is used as the N solvent; when preparing A2PbI... y Br 4-y A2PbBr4, A2PbCl4, A2PbBr y Cl 4-y A2SnI y Br 4-y 、 A2SnI y Cl 4-y When any of the above is used, solvent N is a mixed solvent composed of the polar solvent and toluene in a certain volume ratio. Specifically, in conjunction with... y The value is used to regulate the polarity of the N solvent. Overall, the X-position halide ion contains Cl. - The more components there are, the higher the required polarity. The overall polarity of the N solvent can be controlled by either increasing the volume proportion of the polar solvent or selecting a solvent with inherently higher polarity. y The range of values ​​is 0 < y< 4.

[0023] Specifically, for two-dimensional Ge-based halide perovskites: preparation of A2GeI4, A2GeI y Br 4-y When preparing A₂GeBr₄, the nitrogen solvent should be pure octadecene or a liquid alkane containing 5-16 carbon atoms; when preparing A₂GeCl₄, the nitrogen solvent should be pure toluene; when preparing A₂GeBr₄... y Cl 4-y A2GeI y Cl 4-y In any case, solvent N is a mixed solvent consisting of toluene and liquid alkane containing 5 to 16 carbon atoms in a certain volume ratio, specifically combined with... y The value selection has been optimized. Among them, y The range of values ​​is 0 < y< 4.

[0024] Specifically, for two-dimensional Sn-Ge alloy halide perovskites: preparation of A2Sn x Ge 1-x When using I4, the solvent for N is either pure octadecene or a liquid alkane containing 5–16 carbon atoms; A2Sn is prepared. x Ge 1-x I y Br 4-y A2Sn x Ge 1-x Br4, A2Sn x Ge 1-x Cl4, A2Sn x Ge 1-x Br y Cl4-y A2Sn x Ge 1-x I y Br 4-y 、 A2Sn x Ge 1-x I y Cl 4-y In any of the above cases, solvent N is a mixed solvent consisting of liquid alkane containing 5-16 carbon atoms and toluene mixed in a certain volume, the specific volume ratio depending on... x and y The value selection has been optimized. Among them, x Value range 0 < x< 1, y The value range is 0 < y< 4.

[0025] Specifically, for two-dimensional Pb-Ge alloy halide perovskites: preparation of A2Pb x Ge 1-x I4, A2Pb x Ge 1-x I y Br 4-y In this case, solvent N is a mixed solvent consisting of toluene and liquid alkanes containing 5 to 16 carbon atoms in a certain proportion; the specific volume ratio needs to be determined in conjunction with... x and y Optimize the value; prepare A2Pb x Ge 1-x Br4, A2Pb x Ge 1-x Cl4, A2Pb x Ge 1-x Br y Cl 4-y A2Pb x Ge 1- x I y Cl 4-y When any of the above are used, solvent N is toluene or a mixture of the polar solvent and toluene in a certain volume ratio, the specific volume ratio being determined according to... x and y The value selection has been optimized. Among them, x Value range 0 < x< 1, y The value range is 0 < y< 4.

[0026] Specifically, for two-dimensional Pb-Sn alloy halide perovskites: preparation of A2Pb x Sn 1-xIn I4, the N solvent is a mixed solvent consisting of toluene and liquid alkane containing 5-16 carbon atoms in a certain volume ratio, the specific volume ratio depending on... x Optimize the value selection; prepare A2Pb x Sn 1-x I y Br 4-y A2Pb x Sn 1-x Br4, A2Pb x Sn 1-x Cl4, A2Pb x Sn 1-x Br y Cl 4-y A2Pb x Sn 1-x I y Br 4-y 、 A2Pb x Sn 1-x I y Cl 4-y When using any of the above, solvent N should be pure toluene or a mixture of a polar solvent and toluene in a certain volume ratio, the specific volume ratio depending on... x and y The value selection has been optimized. Among them, x Value range 0 < x< 1, y The value range is 0 < y< 4.

[0027] This invention also provides the application of the two-dimensional metal halide perovskite prepared above in the fabrication of optoelectronic devices.

[0028] For example, by making two-dimensional metal halide perovskites into inks or slurries, large-area, uniform two-dimensional perovskite thin films can be prepared through spraying, printing, and other methods, which greatly facilitates the construction of large-area optoelectronic devices.

[0029] Compared with the prior art, the present invention has the following significant advantages: The method for preparing two-dimensional metal halide perovskites provided by this invention enables one-step synthesis of two-dimensional perovskites at room temperature, and the size of the perovskites can be precisely controlled over a wide range, while avoiding the use of some highly corrosive solvents.

[0030] The two-dimensional perovskite prepared by the method of this invention has flexible and controllable size and can be processed into ink or slurry. Uniform two-dimensional perovskite thin films can be prepared through processes such as spraying and printing. This promotes its application in new semiconductor optoelectronic devices such as light-emitting diodes (LEDs) and photovoltaic devices, and also promotes the large-scale preparation of large-area optoelectronic devices, providing great convenience for promoting its industrialization. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is the UV-Vis absorption spectrum of (OAm)2SnI4 prepared in Example 1 of this invention; Figure 2 This is the steady-state fluorescence spectrum of (OAm)2SnI4 prepared in Example 1 of this invention; Figure 3 These are transmission electron microscope images of (OAm)2SnI4 prepared under different SnI2:amine molar ratios according to Example 1 of the present invention. Figure 4 This is the UV-Vis absorption spectrum of (PEA)2SnBr4 prepared in Example 2 of this invention; Figure 5 This is the UV-Vis absorption spectrum of (OAm)2PbI4 prepared in Example 3 of this invention; Figure 6 This is the steady-state fluorescence spectrum of (OAm)2SnI2Br2 prepared in Example 4 of this invention; Figure 7 This is (OAm)2Pb prepared in Example 5 of the present invention. 0.2 Sn 0.8 The UV-Vis absorption spectrum of I4; Figure 8 This is (OAm)2Pb prepared in Example 5 of the present invention. 0.2 Sn 0.8 Steady-state fluorescence spectrum of I4; Figure 9 It is (OAm)2Sn prepared in Example 6 of this invention. 0.5 Ge 0.5 The UV-Vis absorption spectrum of I4; Figure 10 It is (OAm)2Sn prepared in Example 6 of this invention. 0.5 Ge 0.5 Steady-state fluorescence spectrum of I4; Figure 11 This is the UV-Vis absorption spectrum of (OAm)2SnI4 prepared using different TOP:SnI2 molar ratios in Comparative Example 3 of this invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0035] Example 1 A method for preparing a two-dimensional metal halide perovskite (OAm)₂SnI₄ includes the following steps: First, prepare a TOP-SnI2 solution. Weigh 0.375g of SnI2 and 0.75mL of TOP and place them in a glass reaction flask. Place the flask on a 90℃ heating plate and stir magnetically for about 30 minutes. The SnI2 will completely dissolve in the TOP to form a yellow complex solution. In another glass reaction flask, at room temperature, first add 4mL of n-octane, then measure 30μL of TOP-SnI2 solution. After stirring and mixing thoroughly, add 1μL of oleylamine (OAm). The reaction will occur immediately, and the solution will change from light yellow to red. Figure 1 The UV-Vis absorption spectrum of the red solution clearly shows three exciton absorption peaks located at wavelengths of 430 nm, 510 nm, and 586 nm, which are characteristic absorption peaks of the two-dimensional metal halide perovskite (OAm)₂SnI₄. Further testing of the steady-state fluorescence spectrum, such as... Figure 2 As shown, a fluorescence emission peak at a wavelength of 603 nm appears, further confirming that (OAm)2SnI4 has been generated.

[0036] Furthermore, the size of two-dimensional perovskites can be tuned by changing the molar ratio of SnI2 to amine, such as... Figure 3 As shown, when the molar ratio of SnI2 to amine is 20:1, the average size of the resulting two-dimensional perovskite is approximately 2 nm. Figure 3 a); When the molar ratio of SnI2 to amine is 10:1, the average size of the generated two-dimensional perovskite reaches 32 nm ( Figure 3 b); When the molar ratio of SnI2 to amine is 5:1, the average size of the generated two-dimensional perovskite is approximately 160 nm. Figure 3 c); When the molar ratio of SnI2 to amine is 3:1, the average size of the generated two-dimensional perovskite is approximately 2.6 μm. Figure 3 d).

[0037] Example 2 A method for preparing a two-dimensional metal halide perovskite (PEA)₂SnBr₄ includes the following steps: First, prepare a TOP-SnBr2 solution. Weigh 0.278 g of SnBr2 and 0.5 mL of TOP into a glass reaction flask. Place the flask on a 90°C heating plate and stir magnetically for about 30 minutes. The SnBr2 will completely dissolve in the TOP, forming a light green complex solution. In another glass reaction flask, at room temperature, add 4 mL of toluene, then measure 20 μL of the TOP-SnBr2 solution. After thoroughly mixing, add 1 μL of phenylethylamine (PEA). The reaction occurs immediately, and the solution changes from light green to yellow. Figure 4 The UV-Vis absorption spectrum of the yellow solution was shown, in which the absorption exciton peaks at wavelengths of 398 nm and 446 nm are characteristic absorption peaks of (PEA)2SnBr4, confirming that the two-dimensional perovskite PEA2SnBr4 has been formed.

[0038] Example 3 A method for preparing a metal halide perovskite (OAm)₂PbI₄ includes the following steps: First, prepare a TOPO-PbI2 solution. Weigh 0.461 g of PbI2 and 0.775 g of TOPO into a glass reaction flask. Place the flask on a 90°C heating plate and stir magnetically for about 30 minutes until PbI2 is completely dissolved in TOPO, forming a yellow complex solution. In another glass reaction flask, at room temperature, add 4 mL of toluene, then measure 30 μL of the TOPO-PbI2 solution. After thorough mixing, add 0.5 μL of oleylamine (OAm). The reaction occurs immediately. After about 10 minutes, centrifuge the reaction solution at 8000 rpm, remove the supernatant, and redisperse the lower reaction product in toluene to form a yellow colloid. Further test its UV-Vis absorption spectrum, as shown below. Figure 5 As shown, four absorption exciton peaks were observed at wavelengths of 317 nm, 374 nm, 382 nm, and 491 nm, which are characteristic absorption peaks of (OAm)2PbI4, confirming that the two-dimensional perovskite (OAm)2PbI4 has been formed.

[0039] Example 4 A method for preparing a two-dimensional metal halide perovskite (OAm)2SnI2Br2 includes the following steps: First, prepare the TOP-SnI2-SnBr2 solution. Weigh 0.187g of SnI2 and 0.139g of SnBr2 into a glass reaction flask, then add 0.75mL of TOP. Place the reaction flask on a 90℃ heating plate and magnetically stir for about 30 minutes until SnI2 and SnBr2 are completely dissolved in the TOP, forming a yellow complex solution. In another glass reaction flask, at room temperature, add 4mL of hexane, then measure 30μL of the TOP-SnI2-SnBr2 solution. After thorough mixing, add 2μL of oleylamine. The reaction occurs immediately. After about 10 minutes, centrifuge the reaction solution at 8000rpm, remove the supernatant, and redisperse the lower reaction product in toluene to form a yellow colloid. Further test its steady-state fluorescence spectrum, as shown... Figure 6 As shown, a fluorescence emission peak at a wavelength of 483 nm can be observed, which is the characteristic fluorescence signal of (OAm)2SnI2Br2, confirming that the two-dimensional perovskite (OAm)2SnI2Br2 has been generated.

[0040] Example 5 A two-dimensional metal halide perovskite (OAm)2Pb 0.2 Sn 0.8 The preparation method of I4 includes the following steps: First, a TOP-SnI2-PbI2 solution was prepared. 0.187 g of SnI2 and 0.092 g of PbI2 were weighed and placed in a glass reaction flask. Then, 0.75 mL of TOP was added. The reaction flask was placed on a 90°C heating plate and magnetically stirred for approximately 4 hours. SnI2 and PbI2 completely dissolved in the TOP, forming a yellow complex solution. In another glass reaction flask, at room temperature, 4 mL of a hexane / toluene mixed solvent (volume ratio 4:1) was added. Then, 30 μL of the TOP-PbI2-SnI2 solution was measured and thoroughly mixed. 1 μL of oleylamine was then added. The reaction occurred immediately, and the solution changed from yellow to orange. After approximately 10 minutes of reaction, the reaction solution was centrifuged at 8000 rpm. The supernatant was removed, and the lower reaction product was redispersed in toluene to form an orange colloid. Further testing of its UV-Vis absorption spectrum and steady-state fluorescence spectrum was performed. Figure 7 As shown, four absorption exciton peaks were observed at wavelengths of 318 nm, 375 nm, 410 nm, and 504 nm, respectively. Figure 8 As shown, the fluorescence emission peak observed at 518 nm is (OAm)₂Pb. 0.2 Sn 0.8 The characteristic signal of I4 confirms that the two-dimensional perovskite (OAm)2Pb 0.2 Sn 0.8 I4 has been generated. It should be noted that, to avoid the oxidation of divalent Sn, (OAm)₂Pb was prepared... 0.2Sn 0.8 In the I4 solvent, only TOP was used and not TOPO was used. In order to ensure that PbI2 is fully dissolved in TOP, the dissolution time was extended.

[0041] Example 6 A two-dimensional metal halide perovskite (OAm)2Sn 0.5 Ge 0.5 The preparation method of I4 includes the following steps: First, prepare the TOP-SnI2-GeI2 solution. Weigh 0.188g and 0.163g of GeI2 into a glass reaction flask, then add 0.75mL of TOP. Place the reaction flask on a 90℃ heating plate and stir magnetically for about 30 minutes until GeI2 and SnI2 are completely dissolved in the TOP. In another glass reaction flask, at room temperature, add 3mL of hexane solvent, then measure 30μL of the TOP-SnI2-GeI2 solution. After thorough mixing, add 1μL of oleylamine. The reaction occurs immediately. After about 10 minutes, centrifuge the reaction solution at 10000rpm, remove the supernatant, and redisperse the lower reaction product in hexane to form a yellow colloid. Further test its UV-Vis absorption spectrum and steady-state fluorescence spectrum, as shown below. Figure 9 As shown, absorption exciton peaks located at wavelengths of 430 nm and 479 nm can be observed, respectively; Figure 10 As shown, a fluorescence emission peak at a wavelength of 493 nm can be observed, which is (OAm)2Sn 0.5 Ge 0.5 The characteristic fluorescence signal of I4 confirms that the two-dimensional perovskite (OAm)2Sn 0.5 Ge 0.5 I4 has been generated.

[0042] Comparative Example 1 The preparation of a two-dimensional metal halide perovskite (OAm)₂SnI₄ includes the following steps: First, when preparing the TOP-SnI2 solution, TOP and SnI2 were selected with molar ratios of 1:1, 1.25:1, 1.5:1, 1.75:1, 2:1, and 2.25:1, respectively. After magnetic stirring on a 90℃ heating stage for approximately 30 min, SnI2 was completely dissolved in the TOP to form a TOP-SnI2 complex solution. At room temperature, to maintain an equal amount of SnI2 in the reaction system, 20 μL, 25 μL, 30 μL, 35 μL, 40 μL, and 50 μL of the TOP-SnI2 complex solutions formed by the different molar ratios of TOP and SnI2 were measured and thoroughly mixed with 1 μL of oleylamine (OAm) in 4 mL of hexane. The UV-Vis absorption spectra of the corresponding reaction products were then measured, such as... Figure 11As shown in the diagram, the absorption spectrum reveals that as the TOP:SnI2 molar ratio increases, the three characteristic exciton peaks of (OAm)2SnI4 show a weakening trend. Particularly when the TOP:SnI2 ratio reaches 2.25:1, only two less distinct absorption peaks can be distinguished. This directly reflects a significant deterioration in the quality of (OAm)2SnI4. Therefore, the preferred TOP:SnI2 molar ratio is no more than 2:1. Consequently, in the preparation of two-dimensional metal halide perovskite A2BX4, the molar ratio between trioctylphosphine or trioctylphosphine oxide and metal halide BX2 should not exceed 2:1.

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a two-dimensional metal halide perovskite, characterized by, The two-dimensional metal halide perovskite has a chemical formula of A2BX4, wherein A is one or more of a positive univalent amine ion, B is one or more of Pb 2+ , Sn 2+ , Ge 2+ ; and X is one or more of Cl - , I - , Br - . The preparation method comprises: dissolving BX2 in triphenylphosphine or oxidized triphenylphosphine to form a complex solution, and then reacting with an amine solution corresponding to the cation at position A at room temperature to generate A2BX4.

2. The method of producing a two-dimensional metal halide perovskite according to claim 1, characterized by, The positive monovalent amine ion is one of an alkyl amine ion containing 4-24 carbons, an oleyl amine ion, a phenethyl amine ion, or a thiophene ethyl amine ion.

3. The method of producing a two-dimensional metal halide perovskite according to claim 1, wherein The molar ratio of triphenylphosphine or oxidized triphenylphosphine to BX2 is not less than 1:1, and is preferably 1-2:

1.

4. The method of producing a two-dimensional metal halide perovskite according to any one of claims 1 to 3, characterized in that, The B-site metal ion in BX2 contains Sn. 2+ 、Ge 2+ In one of the following cases, trioctylphosphine solvent is used for BX2; the B-site metal ion in BX2 contains only Pb. 2+ When using trioctylphosphine or trioctylphosphine oxide as solvent, trioctylphosphine oxide is preferred.

5. The method of producing a two-dimensional metal halide perovskite according to claim 2, wherein The molar ratio of BX2 to the amine corresponding to the cation at position A is 1-30:1, and is preferably 1-20:

1.

6. The method of producing a two-dimensional metal halide perovskite according to claim 1, wherein The concentration of BX2 is not less than 0.001 mmol / mL, and is preferably 0.005-0.1 mmol / mL, and more preferably 0.01-0.05 mmol / mL.

7. The method of producing a two-dimensional metal halide perovskite according to claim 1, wherein The solvent of the amine solution corresponding to the cation at position A is an N solvent, which is one or more of a non-polar solvent and a polar solvent; the non-polar solvent is a liquid alkane containing 5-16 carbon atoms, toluene, or octadecene; and the polar solvent is ethyl acetate, methyl acetate, deionized water, dichloromethane, trichloromethane, isopropyl alcohol, n-butanol, ethanol, acetone, or methanol.

8. The method of claim 7, wherein the two-dimensional metal halide perovskite is prepared by the method of any one of claims 1-8. For two-dimensional Sn-based halide perovskites: when preparing A₂SnI₄, the N solvent should be octadecene or a liquid alkane containing 5-16 carbon atoms; for preparing A₂SnBr₄, A₂SnCl₄, and A₂SnBr₄... y Cl 4-y When preparing A₂SnI, toluene is used as the solvent. y Br 4-y 、 A2SnI y Cl 4-y In this case, solvent N is a mixed solvent composed of toluene and liquid alkanes containing 5 to 16 carbon atoms, wherein... y The range of values ​​is 0 < y< 4; or, for two-dimensional Pb-based halide perovskite: when A2PbI4is prepared, the N solvent is selected from toluene; when A2PbI y Br 4-y , A2PbBr4, A2PbCl4, A2PbBr y Cl 4-y , A2SnI y Br 4-y 、 A2SnI y Cl 4-y , A2PbBr4, A2PbCl4, A2PbBr y is in the range of 0 y< 4; or, for two-dimensional Ge-based halide perovskite: preparing A2GeI4, A2GeI y Br 4-y , A2GeBr4, the N solvent is selected from octadecene or liquid alkanes containing 5-16 carbon atoms; when preparing A2GeCl4, the N solvent is selected from toluene; when preparing A2GeBr y Cl 4-y , A2GeI y Cl 4-y , the N solvent is selected from a mixed solvent composed of toluene and liquid alkanes containing 5-16 carbon atoms, wherein, y the value range of x is 0 y< 4; or, for two-dimensional Sn-Ge alloy halide perovskite: preparing A2Sn x Ge 1-x I4, the N solvent is selected from octadecene or liquid alkanes containing 5-16 carbon atoms; preparing A2Sn x Ge 1-x I y Br 4-y , A2Sn x Ge 1-x Br4, A2Sn x Ge 1-x Cl4, A2Sn x Ge 1- x Br y Cl 4-y , A2Sn x Ge 1-x I y Br 4-y 、 A2Sn x Ge 1-x I y Cl 4-y , the N solvent is selected from a mixed solvent composed of liquid alkanes containing 5-16 carbon atoms and toluene, wherein, x the value range of 0 x< 1, y the value range of 0 y< 4; or, for two-dimensional Pb-Ge alloy halide perovskite: preparing A2Pb x Ge 1-x I4、A2Pb x Ge 1-x I y Br 4-y When N is any one of I, Br, Cl, or A2Pb x Ge 1-x Br4、A2Pb x Ge 1-x Cl4、A2Pb x Ge 1-x Br y Cl 4-y 、A2Pb x Ge 1-x I y Cl 4-y When N is any one of I, Br, Cl, or A2Pb x 0 x< 1, y 0 y< 4; or, for two-dimensional Pb-Sn alloy halide perovskite: preparing A2Pb x Sn 1-x I4, the N solvent is selected from a mixed solvent composed of toluene and a liquid alkane containing 5-16 carbon atoms; preparing A2Pb x Sn 1-x I y Br 4-y , A2Pb x Sn 1-x Br4, A2Pb x Sn 1-x Cl4, A2Pb x Sn 1-x Br y Cl 4-y , A2Pb x Sn 1-x I y Br 4-y 、 A2Pb x Sn 1-x I y Cl 4-y , the N solvent is selected from toluene or a mixed solvent composed of a polar solvent and toluene, wherein, x the value range of 0 x< 1, y the value range of 0 y< 4.

9. Use of a two-dimensional metal halide perovskite in the manufacture of a photovoltaic device, characterized in that, The two-dimensional metal halide perovskite is prepared by the method of any one of claims 1-8.

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