A three-dimensional structure germanium-based halide perovskite material and a preparation method and application thereof

Abstract

This application discloses a three-dimensional germanium-based halide perovskite material, its preparation method, and its applications, belonging to the field of functional materials. The chemical formula of the germanium-based halide perovskite material is [NH2CN]GeI3. This material exhibits excellent ferroelectric properties at room temperature and good thermodynamic stability. Large-size hybrid perovskite single crystals can be grown from this compound using a simple and mild solution cooling method; simply cooling its saturated solution to room temperature yields the orange target product. Currently, no three-dimensional organic-inorganic hybrid germanium-based perovskite ferroelectric materials have been developed. The superior ferroelectric, nonlinear optical, and thermochromic properties of the novel compound proposed in this invention have significant practical value for developing novel three-dimensional organic-inorganic hybrid germanium-based perovskite ferroelectric materials, and show promising applications in fields such as ferroelectric memory and smart windows.

Description

Technical Field

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

[0002] Ferroelectrics are an important class of functional materials with wide applications in capacitors, non-volatile memories, and laser frequency converters. The ordered arrangement of dipoles within ferroelectrics creates spontaneous polarization, which can be reversed or reoriented under an applied electric field. Based on this spontaneous polarization, ferroelectric materials often exhibit rich physical properties (such as nonlinear switching effects, pyroelectric effects, piezoelectric effects, electro-optic effects, and photorefractive effects), leading to their widespread application in microelectronics, optoelectronics, sensing technology, aerospace technology, and laser technology, further driving the rapid development of the modern electronic information industry. Therefore, research on ferroelectric materials has become a key research direction integrating chemistry, materials science, and physics, possessing significant scientific value and practical significance for promoting the development of optoelectronics and related industries. Halide perovskite ferroelectrics possess advantages such as light weight, low cost, good mechanical flexibility, ease of low-temperature processing, tunable structure, and biocompatibility, injecting new vitality into the further development of the ferroelectric materials field.

[0003] In recent years, tin-based (Sn) and germanium-based (Ge) hybrid perovskites have gained attention due to their low toxicity and stronger polarizability. 2 The increasingly diverse structures and properties associated with lone pairs of electrons have attracted widespread attention from researchers. In particular, Ge... 2+ 4s 2 The strong stereochemical expression of lone pairs of electrons leads to large octahedral distortions, which in turn results in strong second harmonics and high polarization in germanium-based perovskites. For example, ferroelectricity has been demonstrated in three-dimensional inorganic halide perovskites CsGeX3 (X = Cl, Br, and I), with strong spontaneous polarization (up to 20 μC / cm). 2 (Originating from Ge) 2+ Ion shifts resulting from lone-pair stereochemical activity. Although extensive work has been conducted to investigate the nonlinear optics and ferroelectricity of Ge-based halide perovskites, the ferroelectricity of three-dimensional organic-inorganic hybrid germanium-based perovskites remains to be explored. In summary, the chemical synthesis and preparation of high-performance three-dimensional organic-inorganic hybrid germanium-based perovskite ferroelectric materials have significant practical value. Summary of the Invention

[0004] The purpose of this invention is to provide a large-size three-dimensional germanium-based ferroelectric compound with a simple synthesis method, low cost, mild reaction conditions, high stability, and high saturation polarization intensity, which can be applied to nonlinear optics, ferroelectricity, thermochromism and other fields.

[0005] According to the first aspect of this application, a three-dimensional germanium-based halide perovskite material is provided. Its structure is novel, representing the first example of a hybrid three-dimensional germanium-based perovskite.

[0006] A three-dimensional germanium-based halide perovskite material, wherein the chemical formula of the germanium-based halide perovskite material is [NH2CN]GeI3.

[0007] Optionally, the germanium-based halide perovskite material is made of [GeI6]. 4- It consists of an octahedral framework and an organic cationic cyanamide.

[0008] Optionally, the germanium-based halide perovskite material, at room temperature, belongs to the trigonal crystal system with space group R3m and cell parameters a = 8.469(2), b = 8.469(2). α=90.0°, β=90.0°, γ=120.0°, Z=3,

[0009] This material exhibits ultra-high thermal stability within its halide perovskite domain, with a decomposition temperature of 560 K. Simultaneously, it demonstrates excellent nonlinear optical properties; its nonlinear signal intensity measured under a 2-micron laser is 3.64 times that of AGS (galvanic gallium sulfide silver), and under a 1064-nanometer laser, it is 1.03 times that of KDP (potassium dihydrogen phosphate). UV-Vis absorption spectroscopy reveals an absorption cutoff edge at 589 nm. The material also exhibits excellent ferroelectricity at room temperature, with a saturation polarization of approximately 13.5 μC / cm². 2 As the temperature rises, the material exhibits a reversible color change from orange to red.

[0010] According to a second aspect of this application, a method for preparing a three-dimensional germanium-based halide perovskite material is provided. A simple, mild solution cooling method is used, whereby the saturated solution is cooled to room temperature to obtain the orange target product. Cyanamine and germanium oxide are added to a mixed solution of hydroiodic acid and hypophosphorous acid at room temperature, and after thorough heating and stirring until completely dissolved, the solution is placed in an oven and slowly cooled to crystallize, yielding the cyanamine target compound.

[0011] The preparation method of the germanium-based halide perovskite material described above includes:

[0012] A mixture containing hydroiodic acid, hypophosphorous acid, cyanamide, and GeO2 is stirred and heated to 90-130°C, stirred for 10-20 minutes, and then cooled to room temperature at a rate of 0.5-1.5°C / day to obtain the germanium-based halide perovskite material.

[0013] Optionally, the ratio of GeO2, hydroiodic acid, and hypophosphite is 2-4 mmol: 10-12 ml: 5-7 ml.

[0014] Optionally, the molar ratio of GeO2 to cyanamide is 2-4:4-6.

[0015] Optionally, the weight percentage of HI in hydroiodic acid is 55-58%;

[0016] The weight percentage of H3PO2 in hypophosphorous acid is 50-55%.

[0017] Optionally, the cooling rate is 0.5-1.5℃ / day.

[0018] The above-mentioned germanium-based halide perovskite materials are used in the field of nonlinear optics.

[0019] The above-mentioned germanium-based halide perovskite materials are used in the field of ferroelectricity.

[0020] The above-mentioned germanium-based halide perovskite materials are used in the field of thermochromic properties.

[0021] The beneficial effects that this application can produce include:

[0022] This application provides a three-dimensional germanium-based halide perovskite material, its preparation method, and its applications. This material exhibits ultra-high thermal stability, excellent nonlinear optical properties, and superior ferroelectricity at room temperature. As the temperature increases, the material undergoes a color change from orange to red. The material demonstrates excellent ferroelectric properties at room temperature, with a polarization value as high as 13.5 μC / cm. 2 This compound exhibits excellent thermodynamic stability, with a thermogravimetric decomposition temperature as high as 560 K. Large-size hybrid perovskite single crystals can be prepared using a simple and mild solution cooling method; simply cooling the saturated solution to room temperature yields the orange target product. Currently, no three-dimensional organic-inorganic hybrid germanium-based perovskite ferroelectric materials exist. The superior ferroelectric, nonlinear optical, and thermochromic properties of the novel compound proposed in this invention have significant practical value for developing novel three-dimensional organic-inorganic hybrid germanium-based perovskite ferroelectric materials. It also shows great promise for applications in ferroelectric memory and smart windows. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 prepared in Example 1.

[0024] Figure 2 This is a large-size crystal photograph of the organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 prepared in Example 1.

[0025] Figure 3 The thermal stability diagram of the organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 prepared in Example 1 is shown.

[0026] Figure 4 The image shows the nonlinear intensity of the organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 prepared in Example 1 under a 2-micron laser.

[0027] Figure 5 The nonlinear intensity of the organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 prepared in Example 1 under a 1064 nm laser.

[0028] Figure 6 The absorption spectrum of the organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 prepared in Example 1 is shown.

[0029] Figure 7 The thermochromic diagram of the organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 prepared in Example 1.

[0030] Figure 8 The hysteresis loop diagram is shown for the three-dimensional germanium-based ferroelectric material [NH2CN]GeI3, an organic-inorganic hybrid perovskite, prepared in Example 1. Detailed Implementation

[0031] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0032] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0033] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0034] The analysis method in the embodiments of this application is as follows:

[0035] The instrument used for the crystallographic data analysis of the materials was an X-ray single crystal diffractometer, Agilent Technologies, Bruker D8, with a Mo target X-ray source.

[0036] The instrument used for thermal stability analysis was a comprehensive thermal analyzer, Netzsch STA-449C, Germany, under conditions ranging from room temperature to 800 degrees Celsius.

[0037] The instrument used for nonlinear intensity analysis was an Nd:YAG laser from the Anhui Institute of Optics and Precision Instruments, and the conditions were at room temperature.

[0038] The instrument used for absorption spectroscopy analysis was a UV-Vis-NIR spectrophotometer, PerkinElmer, USA, Lambda 950, with testing conditions of 400-800 nm.

[0039] The instrument used for hysteresis loop analysis was a ferroelectric analyzer, Radiant Premier II, manufactured by Texas Instruments International Ltd., under the conditions of room temperature and 10 Hz.

[0040] Example 1: Chemical preparation of organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3

[0041] A method for synthesizing the organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 includes the following sequential steps:

[0042] (1) Dissolve cyanamide (5 mmol) and GeO2 (3 mmol) in 12 mL of hydroiodic acid and 6 mL of hypophosphoric acid, heat to 120 °C, and stir for 20 min to allow them to react completely.

[0043] (2) After the solution is slowly cooled and crystallized in a temperature-controlled oven at a rate of 0.5℃ / day, filtered and dried, orange flaky target product organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 is obtained.

[0044] At room temperature, this material belongs to the trigonal crystal system with space group R3m and cell parameters a = 8.469(2), b = 8.469(2). α=90.0°, β=90.0°, γ=120.0°, Z=3,

[0045] Figure 1 Here is a schematic diagram of its structure, provided by [GeI6]. 4- It consists of an octahedral framework and an organic cationic cyanamide. The cyanamide cation is in a disordered state within the pores, and cyanamide can form NH···I hydrogen bonds with the inorganic framework, [GeI6]. 4- The octahedron exhibits obvious distortion, with significant inhomogeneity in Ge-I bond length and I-Ge-I bond angle, causing the positive and negative charges in the structure to deviate from their original central positions, thereby forming an electric dipole moment in [NH2CN]GeI3.

[0046] Figure 2 The crystal photographs show that crystals can be grown to large single crystals on the centimeter scale.

[0047] Figure 3 The thermal stability diagram shows that the material has extremely high thermal stability, with a decomposition temperature of 560K.

[0048] Example 2: Application of the organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH2CN]GeI3 in the field of ferroelectric memory

[0049] The [NH2CN]GeI3 obtained in Example 1 was subjected to hysteresis loop testing using the dual-wavelength method on a Radiant Premier II. Figure 8 As shown, the saturation polarization intensity is approximately 13.5 μC / cm at room temperature. 2 The material exhibits good stability and fatigue resistance, making it a candidate material for ferroelectric memory.

[0050] Example 3: Application of organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric materials in nonlinear optics and thermochromic fields

[0051] The organic-inorganic hybrid perovskite three-dimensional germanium-based ferroelectric material [NH₂CN]GeI₃ obtained in Example 1 exhibits a non-centrosymmetric structure at room temperature. Second-order nonlinear optical properties were tested using an Nd:YAG laser. The material showed good nonlinear optical properties; the nonlinear signal intensity was measured using a 2-micrometer laser with a pulse duration of 5 ns. Figure 4 As shown, AGS (galvanium sulfide silver) was used as a comparison to evaluate the nonlinearity of the material, which is 3.64 times that of AGS. Its nonlinear signal intensity was measured under a 1064nm laser, as shown... Figure 5 As shown, this represents a 1.03-fold increase compared to the KDP (potassium dihydrogen phosphate) standard. Absorption spectroscopy was performed using a UV-Vis-IR spectrophotometer (Lamda 950). Figure 6 As shown, the absorption cutoff edge appears at 589 nm. These results indicate that the material has application value in the field of nonlinear optics. Figure 7 The thermochromic properties exhibited by this study also have potential research value.

[0052] 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 implementation cases and fall within the scope of the technical solution.

Claims

1. A three-dimensional germanium-based halide perovskite material, characterized in that, The chemical formula of the germanium-based halide perovskite material is [NH2CN]GeI3.

2. The germanium-based halide perovskite material according to claim 1, characterized in that, The germanium-based halide perovskite material is composed of [GeI6]. 4- It consists of an octahedral framework and an organic cationic cyanamide.

3. The germanium-based halide perovskite material according to claim 1, characterized in that, The germanium-based halide perovskite material, at room temperature, belongs to the trigonal crystal system with space group R3m and cell parameters a = 8.469(2), b = 8.469(2). α=90.0°, β=90.0°, γ=120.0°, Z=3, 4. The method for preparing the germanium-based halide perovskite material according to any one of claims 1 to 3, characterized in that, include: A mixture containing hydroiodic acid, hypophosphorous acid, cyanamide, and GeO2 is stirred and heated to 90-130°C, stirred for 10-20 minutes, and then cooled to room temperature at a rate of 0.5-1.5°C / day to obtain the germanium-based halide perovskite material.

5. The preparation method according to claim 4, characterized in that, The ratio of GeO2, hydroiodic acid, and hypophosphite is 2-4 mmol: 10-12 ml: 5-7 ml.

6. The preparation method according to claim 4, characterized in that, The molar ratio of GeO2 to cyanamide is 2-4:4-6.

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 application of the germanium-based halide perovskite material according to any one of claims 1 to 3 in the field of nonlinear optics.

9. The application of the germanium-based halide perovskite material according to any one of claims 1 to 3 in the field of ferroelectricity.

10. The application of the germanium-based halide perovskite material according to any one of claims 1 to 3 in the field of thermochromism.

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