Two-dimensional germanium-based perovskite ferroelectric semiconductor materials, methods of preparation, and applications thereof

Abstract

This application discloses a two-dimensional germanium-based perovskite ferroelectric semiconductor material, its preparation method, and its applications, belonging to the field of materials science. The molecular formula of the two-dimensional germanium-based perovskite ferroelectric semiconductor material is [CH3(CH2)]. n The molecule is NH3]2CsGe2I7, where n = 2, 3, or 4. This material possesses excellent physicochemical properties, such as semiconductor characteristics, ferroelectricity, and piezoelectricity. The preparation method of this invention allows for the preparation of this material using a simple solution method at low cost. This material has potential applications in ferroelectric, optoelectronic, and other fields.

Description

Technical Field

[0001] This application relates to a two-dimensional germanium-based perovskite ferroelectric semiconductor material, its preparation method, and its application, belonging to the field of materials. Background Technology

[0002] Two-dimensional (2D) semiconductors have attracted widespread research interest in optoelectronic applications due to their significant anisotropy, unique electronic band structure, and other novel properties. Compared to three-dimensional (3D) semiconductors, charge in 2D semiconductors tends to transport in-plane, resulting in a high degree of correlation between their optical and electrical properties and orientation. This makes 2D semiconductor materials promising for applications such as polarization photodetectors. Excitingly, the discovery of ferroelectricity in 2D semiconductors has led to entirely new phenomena, such as the negative piezoelectric effect and bulk photovoltaic effect. The coupling of anisotropy, ferroelectricity, and semiconductor properties will play a crucial role in next-generation optoelectronic applications. However, most currently reported 2D ferroelectric semiconductor systems are subject to strict lattice symmetry constraints, and their ferroelectric polarization and other properties are not entirely satisfactory. This has prompted researchers to further explore new high-performance ferroelectric semiconductor systems.

[0003] In recent years, two-dimensional organic-inorganic halide perovskites have attracted widespread attention as a new class of excellent semiconductor materials. Their ordered organic cations and highly twisted inorganic framework provide an ideal platform for symmetry breaking and ferroelectric polarization. Through the unremitting efforts of researchers in recent years, several two-dimensional organic-inorganic halide perovskite ferroelectrics have been designed and synthesized, such as (benzylamine)₂PbCl₄ and (isobutylamine)₂PbCl₄. Recently, germanium-based halide perovskites have become one of the most promising alternatives due to their lead-like electronic structure and lower toxicity. Notably, this structure, containing strong lone pair electron stereochemical activity, can bring many excellent optoelectronic properties, including high defect tolerance and carrier mobility. In particular, Ge 2+ The stereochemical activity of the lone pair electrons leads to strong octahedral distortion and symmetry breaking, which favors strong second harmonic effects and large ferroelectric spontaneous polarization. For example, strong ferroelectric polarization is observed in three-dimensional germanium-iodine-based perovskites CsGeX3 (where X = Cl, Br, and I) and one-dimensional (dimethylamine)GeI3, where Ge 2+ The strong stereochemical activity of lone pair electrons plays a crucial role in promoting ion shift and ferroelectric ordering. However, the exploration of two-dimensional germanium-based perovskite ferroelectric materials remains in its infancy. Therefore, exploring two-dimensional germanium-based halide perovskite ferroelectric semiconductors is of great significance for understanding the interaction between two-dimensional ferroelectricity and semiconductor physics. Summary of the Invention

[0004] According to the first aspect of this application, a two-dimensional germanium-based perovskite ferroelectric semiconductor material is provided. This material possesses excellent physicochemical properties, such as semiconductor characteristics, ferroelectricity, and piezoelectricity.

[0005] A two-dimensional germanium-based perovskite ferroelectric semiconductor material, wherein the molecular formula of the two-dimensional germanium-based perovskite ferroelectric semiconductor material is [CH3(CH2)]. n NH3]2CsGe2I7;

[0006] Where n = 2, 3 or 4.

[0007] Alternatively, when n=2, α=90°, β=90°, γ=90°, It belongs to the orthorhombic crystal system, mm2 point group, and Cmc21 space group;

[0008] When n=3, α=90°, β=90°, γ=90°, It belongs to the orthorhombic crystal system, mm2 point group, and Cmc21 space group;

[0009] When n=4 α=90°, β=90°, γ=90°, It belongs to the orthorhombic crystal system, mm2 point group, and Cmc21 space group.

[0010] Optionally, divalent germanium ions are connected to halogens to form octahedra, and the octahedra are connected at common corners to form an inorganic framework; organic amine cations are located between the inorganic layers, separating the inorganic layers and balancing the charges; organic amine cations are connected to the inorganic framework through hydrogen bonds, and van der Waals forces exist between the inorganic layers.

[0011] According to a second aspect of this application, a method for preparing a two-dimensional germanium-based perovskite ferroelectric semiconductor material is provided.

[0012] The method for preparing the two-dimensional germanium-based perovskite ferroelectric semiconductor material described above is characterized by comprising the following steps:

[0013] (1) Add GeO2 to a mixed solution of hydroiodic acid and hypophosphorous acid, stir and heat to 90-110℃, and then continue stirring for 30-40 minutes;

[0014] (2) Subsequently, an organic cation (CH3(CH2)) was added. n NH3 and Cs2CO3, continue heating and stirring until a clear solution is obtained;

[0015] Where n = 2, 3 or 4;

[0016] (3) Finally, after cooling to room temperature, the two-dimensional germanium-based perovskite ferroelectric semiconductor material is obtained.

[0017] Optionally, the ratio of GeO2, hydroiodic acid, and hypophosphite is 2 mmol: 5-10 ml: 2-4 ml.

[0018] Alternatively, GeO2, (CH3(CH2)) n The molar ratio of NH3 to Cs2CO3 is 2-2.5:2-2.5:0.5-1.

[0019] Optionally, the weight percentage of HI in hydroiodic acid is 55-58%;

[0020] The weight percentage of H3PO2 in hypophosphorous acid is 50%.

[0021] Optionally, the cooling rate is 0.5-2℃ / day.

[0022] The above-mentioned two-dimensional germanium-based perovskite ferroelectric semiconductor materials are used in the fields of ferroelectricity, pyroelectricity, and piezoelectricity.

[0023] The above-mentioned two-dimensional germanium-based perovskite ferroelectric semiconductor materials are used in dielectric switches, phase change thermal storage, light-absorbing elements, and broadband photoelectric detection.

[0024] The beneficial effects that this application can produce include:

[0025] This application provides a two-dimensional germanium-based perovskite ferroelectric semiconductor material, its preparation method, and its applications. This material possesses excellent physicochemical properties, such as semiconductor characteristics, ferroelectricity, and piezoelectricity. The preparation method of this invention allows for the preparation of this material using a simple solution method, resulting in low cost. This material has potential applications in ferroelectric, optoelectronic, and other fields. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a two-dimensional germanium-based perovskite ferroelectric semiconductor material. 1 represents the organic cation CH3(CH2)2NH3. + (n = 2, 3, 4), where 2 is divalent metal germanium (Ge), 3 is halide ion iodine (I), 2 and 3 form germanium-iodine chemical bonds, constituting an octahedron, which are connected by sharing corners to form an inorganic layer. 4 is cesium ion.

[0027] Figure 2 This is a structural packing diagram of the [CH3(CH2)2NH3]2CsGe2I7 crystal from Example 1.

[0028] Figure 3 This is a structural packing diagram of the [CH3(CH2)3NH3]2CsGe2I7 crystal from Example 2.

[0029] Figure 4This is a structural packing diagram of the [CH3(CH2)4NH3]2CsGe2I7 crystal from Example 3.

[0030] Figure 5 The hysteresis loop of the [CH3(CH2)2NH3]2CsGe2I7 crystal in Example 1.

[0031] Figure 6 The hysteresis loop of the [CH3(CH2)3NH3]2CsGe2I7 crystal in Example 2.

[0032] Figure 7 The hysteresis loop of the [CH3(CH2)4NH3]2CsGe2I7 crystal in Example 3.

[0033] Figure 8 The differential scanning calorimetry curve of [CH3(CH2)3NH3]2CsGe2I7 in Example 2 is shown.

[0034] Figure 9 Temperature-dependent dielectric constant test of [CH3(CH2)3NH3]2CsGe2I7 in Example 2.

[0035] Figure 10 The UV-Vis absorption spectrum of [CH3(CH2)3NH3]2CsGe2I7 in Example 2 is shown.

[0036] Figure 11 The current-time curve of [CH3(CH2)3NH3]2CsGe2I7 in Example 2 is shown.

[0037] Figure 12 The polar coordinate curves of the optical polarization angle versus photocurrent of the polarization photodetector based on the [CH3(CH2)3NH3]2CsGe2I7 single crystal from Example 2 are shown. Detailed Implementation

[0038] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0039] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0040] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0041] The analysis method in the embodiments of this application is as follows:

[0042] The crystallographic data analysis was performed using a Bruker D8 X-ray single-crystal diffractometer at 300K, with data collected using a Mo light source.

[0043] The instrument used for hysteresis loop analysis was a Radiant Premier II ferroelectric analyzer from Texas Instruments International Ltd., with a test temperature of 300K.

[0044] The differential scanning calorimetry (DSC) curve analysis was performed using a NETZSCH 200F3 DSC differential scanning calorimeter from NETZSCH GmbH, Germany, with a test temperature range of 310K to 500K.

[0045] The instrument used for the temperature-dependent dielectric constant test and analysis was an impedance analyzer from Changzhou Tonghui Electronics Co., Ltd., model TH2828A, with a test temperature range of 350K~440K.

[0046] The instrument used for UV-Vis absorption spectroscopy analysis was a PerkinElmer UV-Vis-NIR spectrophotometer, model Lambda950, with a test temperature of 300K and a spectral range of 350nm–1000nm. Instruments used for photoelectric performance analysis included a Keithel electrometer (6517B / E), a Solvay Optoelectronics Technology Co., Ltd. laser diode (LP637-MF300), and a Solvay Optoelectronics Technology Co., Ltd. optical power meter (PM100D). The test temperature was 300K.

[0047] Example 1

[0048] A method for synthesizing the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)2NH3]2CsGe2I7 includes the following sequential steps:

[0049] (1) Add GeO2 to a mixed solution of hydroiodic acid and hypophosphoric acid, stir and heat to 90°C, and then continue stirring for 35 minutes;

[0050] (2) Then add n-propylamine and Cs2CO3, and continue heating and stirring until a clear solution is obtained;

[0051] (3) Finally, after cooling to room temperature, the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)2NH3]2CsGe2I7 is obtained;

[0052] The weight percentage of HI in hydroiodic acid is 57%.

[0053] The weight percentage of H3PO2 in hypophosphorous acid is 50%.

[0054] The amounts of GeO2, hydroiodic acid, and hypophosphite used are 2 mmol of GeO2, 10 ml of hydroiodic acid, and 4 ml of hypophosphite.

[0055] The amounts of GeO2, n-propylamine, and Cs2CO3 were 2 mmol, 2 mmol, and 0.5 mmol, respectively.

[0056] The clarified solution obtained in step (2) was cooled from 75°C to 25°C at a rate of 0.5°C / day to obtain a bulk two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)2NH3]2CsGe2I7.

[0057] Example 2

[0058] A method for synthesizing the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 includes the following sequential steps:

[0059] (1) Add GeO2 to a mixed solution of hydroiodic acid and hypophosphoric acid, stir and heat to 90°C, and then continue stirring for 35 minutes;

[0060] (2) Then add n-butylamine and Cs2CO3, and continue heating and stirring until a clear solution is obtained;

[0061] (3) Finally, after cooling to room temperature, the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 is obtained;

[0062] The weight percentage of HI in hydroiodic acid is 57%.

[0063] The weight percentage of H3PO2 in hypophosphorous acid is 50%.

[0064] The amounts of GeO2, hydroiodic acid, and hypophosphoric acid used were 2 mmol of GeO2, 10 ml of hydroiodic acid, and 4 ml of hypophosphoric acid; the amounts of GeO2, n-butylamine, and Cs2CO3 used were 2 mmol, 2 mmol, and 0.5 mmol, respectively.

[0065] The clarified solution obtained in step (2) was cooled from 75°C to 25°C at a rate of 1°C / day to obtain a bulk two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7.

[0066] Example 3

[0067] A method for synthesizing the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)4NH3]2CsGe2I7 includes the following sequential steps:

[0068] (1) Add GeO2 to a mixed solution of hydroiodic acid and hypophosphoric acid, stir and heat to 90°C, and then continue stirring for 35 minutes;

[0069] (2) Then add n-pentylamine and Cs2CO3, and continue heating and stirring until a clear solution is obtained;

[0070] (3) Finally, after cooling to room temperature, the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)4NH3]2CsGe2I7 is obtained;

[0071] The weight percentage of HI in hydroiodic acid is 57%.

[0072] The weight percentage of H3PO2 in hypophosphorous acid is 50%.

[0073] The amounts of GeO2, hydroiodic acid, and hypophosphite used are 2 mmol of GeO2, 10 ml of hydroiodic acid, and 4 ml of hypophosphite.

[0074] The amounts of GeO2, n-pentylamine, and Cs2CO3 were 2 mmol, 2 mmol, and 0.5 mmol, respectively.

[0075] The clarified solution obtained in step (2) was cooled from 75°C to 25°C at a rate of 2°C / day to obtain a bulk two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)4NH3]2CsGe2I7.

[0076] A schematic diagram of the structure of a two-dimensional germanium-based perovskite ferroelectric semiconductor material is shown below. Figure 1 As shown. 1 is an organic cation (CH3(CH2)2NH3). + (n = 2, 3, 4), where 2 is divalent germanium (Ge), 3 is iodine (I), and 2 and 3 form germanium-iodine bonds, constituting an octahedron. The octahedrons are connected by sharing corners to form an inorganic layer. 4 is cesium ion. Organic amine cations are located between the inorganic layers, separating them and balancing their charges; the organic amine cations are connected to the inorganic framework by hydrogen bonds, and van der Waals forces exist between the inorganic layers.

[0077] Figure 2 This is a structural packing diagram of the [CH3(CH2)2NH3]2CsGe2I7 crystal from Example 1. Divalent germanium ions and iodine ions are linked to form octahedrons, which are connected at common angles to form an inorganic layer. Cesium ions are located in the voids formed by the octahedral connections. Organic amine cations (CH3(CH2)2NH3) + It is located in the inorganic interlayer and connected to the inorganic framework by hydrogen bonds. The cell parameters of [CH3(CH2)2NH3]2CsGe2I7 are as follows: α=90°, β=90°, γ=90°, It belongs to the orthorhombic crystal system, mm2 point group, and Cmc21 space group.

[0078] Figure 3This is a structural packing diagram of the [CH3(CH2)3NH3]2CsGe2I7 crystal from Example 2, in which divalent germanium ions and iodine ions are connected to form octahedra, and the octahedra are connected at common angles to form an inorganic layer. Cesium ions are located in the voids formed by the octahedral connections, and the organic amine cation CH3(CH2)3NH3 + It is located in the inorganic interlayer and connected to the inorganic framework by hydrogen bonds. The cell parameters of [CH3(CH2)3NH3]2CsGe2I7 are as follows: α=90°, β=90°, γ=90°, It belongs to the orthorhombic crystal system, mm2 point group, and Cmc21 space group.

[0079] Figure 4 This is a structural packing diagram of the [CH3(CH2)4NH3]2CsGe2I7 crystal from Example 3, in which divalent germanium ions and iodine ions are connected to form octahedra, and the octahedra are connected at common angles to form an inorganic layer. Cesium ions are located in the voids formed by the octahedral connections, and the organic amine cation CH3(CH2)4NH3 + It is located in the inorganic interlayer and connected to the inorganic framework by hydrogen bonds. The cell parameters of [CH3(CH2)4NH3]2CsGe2I7 are as follows: α=90°, β=90°, γ=90°, It belongs to the orthorhombic crystal system, mm2 point group, and Cmc21 space group.

[0080] Example 4

[0081] Applications of two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)2NH3]2CsGe2I7 in ferroelectric, pyroelectric, and piezoelectric fields.

[0082] The hysteresis loop of the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)2NH3]2CsGe2I7 obtained in Example 1 was tested. Before the phase transition (300K), the material exhibited a typical ferroelectric hysteresis loop, such as... Figure 4 As shown, this indicates that the material has great application potential in ferroelectric, pyroelectric, and piezoelectric fields.

[0083] Example 5

[0084] Applications of two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 in ferroelectric, pyroelectric, and piezoelectric fields.

[0085] The hysteresis loop of the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 obtained in Example 2 was tested. Before the phase transition (300K), the material exhibited a typical ferroelectric hysteresis loop, such as... Figure 5As shown, this indicates that the material has great application potential in ferroelectric, pyroelectric, and piezoelectric fields.

[0086] Example 6

[0087] Applications of two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)4NH3]2CsGe2I7 in ferroelectric, pyroelectric, and piezoelectric fields.

[0088] The hysteresis loop of the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)4NH3]2CsGe2I7 obtained in Example 3 was tested. Before the phase transition (300K), the material exhibited a typical ferroelectric hysteresis loop, such as... Figure 6 As shown, this indicates that the material has great application potential in ferroelectric, pyroelectric, and piezoelectric fields.

[0089] Example 7

[0090] Applications of two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 in dielectric switching and phase change thermal storage

[0091] Temperature-dependent dielectric constant tests were performed on the two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 obtained in Example 2. A distinct step-type phase transition was observed at the ferroelectric-paraelectric structural transition point (412 K), revealing the switchability between low ("off") and high ("on") dielectric states centered around 412 K. Figure 8 As shown. The relevant results indicate that the material has potential application value in fields such as dielectric switches. Simultaneously, the differential scanning calorimetry curves show that [CH3(CH2)3NH3]2CsGe2I7 exhibits significant endothermic and exothermic processes during the phase transition, such as... Figure 9 As shown, this material has potential application value in fields such as phase change thermal energy storage technology.

[0092] Example 8

[0093] Applications of two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 in the field of light-absorbing elements

[0094] The two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 obtained in Example 2 was subjected to ultraviolet-visible absorption spectroscopy. The test results are as follows: Figure 10 As shown, its absorption cutoff edge reaches 750nm, which indicates that it has a wide light absorption range and strong light absorption capability, making it an ideal candidate for light-absorbing materials with great potential in the fields of light-absorbing elements and solar cells.

[0095] Example 9

[0096] Applications of two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 in broadband photodetector applications

[0097] The photoelectric properties of the two-dimensional germanium-based halide perovskite ferroelectric semiconductor (CH3(CH2)3NH3)2CsGe2I7 crystal obtained in Example 2 were tested. The crystal was first pretreated by drying and cutting, and then electrode materials were deposited on the crystal surface using a vapor deposition method to fabricate a photodetector. A 637nm laser was used for photoelectric testing. Figure 11 As shown. When the incident light intensity is 25.32 mW / cm². 2 At this time, the ratio of photocurrent to dark current is approximately 800, exhibiting excellent photoconductivity.

[0098] Example 10

[0099] Applications of two-dimensional germanium-based halide perovskite ferroelectric semiconductor [CH3(CH2)3NH3]2CsGe2I7 in polarization photodetector

[0100] In Example 2, [CH3(CH2)3NH3]2CsGe2I7 is a two-dimensional layered perovskite with strong intrinsic anisotropy, including anisotropy in its structure and light absorption properties. Meanwhile, (n-butylamine)2CsGe2I7 is a ferroelectric material, exhibiting a bulk photovoltaic effect dependent on the polarization angle. Using a large-size crystal of (n-butylamine)2CsGe2I7, the polarization photodetector performance was tested. The figure shows a polarization photodetector device based on a single crystal of (n-butylamine)2CsGe2I7. The laser beam becomes linearly polarized after passing through a polarizer. Then, rotating the half-wave plate changes the polarization direction of the linearly polarized light. Finally, the polarized light illuminates the sample, and the photocurrent-polarization angle change curve is recorded to study its polarization photodetector performance. An intensity of 50 mW / cm² was used here. 2 The 637nm laser was tested under a 0V bias voltage. Figure 12 As shown, the photodetector based on [CH3(CH2)3NH3]2CsGe2I7 single crystal has excellent polarization photodetection response performance, with a dichroism ratio of about 1.68, which makes this material promising for application in the field of polarization photodetection.

[0101] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent embodiments and fall within the scope of the technical solution.

Claims

1. A two-dimensional germanium-based perovskite ferroelectric semiconductor material, characterized in that, The molecular formula of the two-dimensional germanium-based perovskite ferroelectric semiconductor material is [CH3(CH2)]. n NH3]2CsGe2I7; Where n = 2, 3 or 4.

2. The two-dimensional germanium-based perovskite ferroelectric semiconductor material according to claim 1, characterized in that, When n=2, α=90°, β=90°, γ=90°, It belongs to the orthorhombic crystal system, mm2 point group, and Cmc21 space group; When n=3, α=90°, β=90°, γ=90°, It belongs to the orthorhombic crystal system, mm2 point group, and Cmc21 space group; When n=4 α=90°, β=90°, γ=90°, It belongs to the orthorhombic crystal system, mm2 point group, and Cmc21 space group.

3. The two-dimensional germanium-based perovskite ferroelectric semiconductor material according to claim 1, characterized in that, Divalent germanium ions connect with haloiodine ions to form octahedrons, and the octahedrons are connected at common angles to form an inorganic framework; organic amine cations are located between the inorganic layers, separating the inorganic layers and balancing the charges; organic amine cations are connected to the inorganic framework through hydrogen bonds, and van der Waals forces exist between the inorganic layers.

4. The method for preparing the two-dimensional germanium-based perovskite ferroelectric semiconductor material according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Add GeO2 to a mixed solution of hydroiodic acid and hypophosphorous acid, stir and heat to 90-110℃, and then continue stirring for 30-40 minutes; (2) Subsequently, an organic cation (CH3(CH2)) was added. n NH3 and Cs2CO3, continue heating and stirring until a clear solution is obtained; Where n = 2, 3 or 4; (3) Finally, after cooling to room temperature, the two-dimensional germanium-based perovskite ferroelectric semiconductor material is obtained.

5. The preparation method according to claim 4, characterized in that, The ratio of GeO2, hydroiodic acid, and hypophosphite is 2 mmol: 5-10 ml: 2-4 ml.

6. The preparation method according to claim 4, characterized in that, GeO2, CH3(CH2) n The molar ratio of NH3 to Cs2CO3 is 2-2.5:2-2.5:0.5-1.

7. The preparation method according to claim 4, characterized in that, The weight percentage of HI in hydroiodic acid is 55-58%. The weight percentage of H3PO2 in hypophosphorous acid is 50-55%.

8. The preparation method according to claim 4, characterized in that, The cooling rate is 0.5-2℃ / day.

9. The application of the two-dimensional germanium-based perovskite ferroelectric semiconductor material according to any one of claims 1 to 3 in the fields of ferroelectricity, pyroelectricity, and piezoelectricity.

10. The application of the two-dimensional germanium-based perovskite ferroelectric semiconductor material according to any one of claims 1 to 3 in the fields of dielectric switches, phase change thermal storage, light-absorbing elements, and broadband photoelectric detection.

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