Method for intercepting high-pressure phase of Cd-based metal halide

Abstract

The invention is applicable to the technical field of perovskite luminescent materials, and provides a method for intercepting a high-pressure phase of a Cd-based metal halide, which comprises the following steps of: pre-pressing a stainless steel metal sheet by using a diamond anvil cell press, and drilling a hole groove at an indentation to serve as a pressure cavity; cd-based metal halide crystals are placed in a pressure cavity, mineral oil is added to serve as a pressure transmitting medium, pressurization is conducted, ruby serves as a calibration pressure substance in the pressurization process, the chemical general formula of the Cd-based metal halide crystals is [BPy] 2CdX4, [BPy] 2 is C18H28N2, and X is selected from I, Br and Cl; the performance of the Cd-based metal halide crystal is regulated and controlled through the pressure, after the pressure is slowly released, the emission phenomenon different from the initial emission phenomenon is shown, and the high-pressure phase of the Cd-based metal halide is successfully intercepted. On the basis of pressure regulation, a part of amorphous phase can be reserved, meanwhile, on the premise that other components are not introduced, the inter-atomic distance and interaction in the material are precisely regulated, the band gap of the material is changed, and then the high-pressure phase of the Cd-based metal halide is successfully intercepted.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite luminescent materials, and particularly relates to a method for intercepting the high-pressure phase of Cd-based metal halides. Background Art

[0002] Due to their excellent light absorption properties, large exciton binding energy, and broadband emission, perovskite luminescent materials have a wide range of applications in the fields of green energy, white lighting, and photoelectric sensors. Among them, the pressure-induced emission (PIE) behavior of halide perovskites has attracted extensive attention and has potential application prospects in the field of pressure sensing. However, high-pressure reversibility greatly inhibits practical applications. In view of this goal, it is extremely important to find and design a method for intercepting the excellent high-pressure phase of perovskites, which can precisely regulate the material properties without introducing other components, obtain highly efficient and stable perovskite luminescent materials with multi-color gamut coverage, and play a role in different scenarios, such as tunable lighting and external stimulus response.

[0003] In the prior art, it has been proposed that the emission color gamut can be tuned by gradiently adjusting the proportion of different halogen atoms in the perovskite material and changing the bandgap of the material. However, phase segregation and defects caused by different halogens during use lead to poor material stability and a decrease in photoluminescence quantum yield. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a method for intercepting the high-pressure phase of Cd-based metal halides, aiming to solve the problems proposed in the above background art.

[0005] The embodiments of the present invention are implemented as follows. A method for intercepting the high-pressure phase of Cd-based metal halides includes the following steps: Pre-press a stainless-steel metal sheet using a diamond anvil press, and drill a hole groove at the indentation as a pressure chamber; Place the Cd-based metal halide crystal into the pressure chamber, add mineral oil as a pressure-transmitting medium, and apply pressure. During the pressure application process, ruby is used as a pressure-calibrating substance. The chemical general formula of the Cd-based metal halide crystal is [BPy]2CdX4, where [BPy]2 is C 18 H 28 N2, and X is taken from I, Br, Cl; Regulate the properties of the Cd-based metal halide crystal through pressure. After slowly releasing the pressure, an emission phenomenon different from the initial one is exhibited, thereby realizing the interception of the high-pressure phase of the Cd-based metal halide.

[0006] Preferably, the diamond used in the diamond anvil press is a type-IIa diamond.

[0007] Preferably, the diameter of the hole groove is 150 μm, and the size of the Cd-based metal halide crystal is 50-100 μm in diameter.

[0008] Preferably, when X is I, Br, and Cl respectively, the pressure during the pressurization process is increased from normal temperature and pressure to 26 GPa, 30 GPa, and 30 GPa respectively.

[0009] Preferably, when X is I, through pressure regulation, the emission color gamut changes from the yellow light emission CIE chromaticity coordinates (0.361, 0.400) in the initial state to the orange light emission CIE chromaticity coordinates (0.397, 0.403) after pressure treatment.

[0010] Preferably, when X is Br, through pressure regulation, the emission color gamut changes from the cyan-yellow light emission CIE chromaticity coordinates (0.362, 0.399) in the initial state to the warm yellow light emission CIE chromaticity coordinates (0.366, 0.422) after pressure treatment.

[0011] Preferably, when X is Cl, through pressure regulation, the emission color gamut changes from the blue light emission CIE chromaticity coordinates (0.153, 0.029) in the initial state to the orange-yellow light emission CIE chromaticity coordinates (0.402, 0.413) after pressure treatment.

[0012] A method for intercepting the high-pressure phase of Cd-based metal halides provided by an embodiment of the present invention synthesizes three cadmium halide crystals by substituting the X site, and realizes pressure-induced fluorescence enhancement through the synergistic effect of the self-trapped state emission induced by applying an external pressure and the organic cations and inorganic substances. When X is Br and Cl, bright warm yellow light and orange-yellow light are generated at normal temperature and pressure through pressure regulation respectively. The pressure treatment can retain part of the amorphous phase and enhance the hydrogen bond interaction, thereby successfully intercepting the excellent high-pressure phase of Cd-based metal halides and effectively tuning the luminescent color gamut of the material; in addition, by using pressure, a clean means, the interatomic distance and interaction inside the material can be precisely regulated without introducing other components, optimizing the electro-acoustic coupling strength, changing the band gap of the material, and making the luminescent color gamut of the material [BPy]2CdI4 change from yellow light emission (CIE chromaticity coordinates (0.361, 0.400)) in the initial state to orange light emission (CIE chromaticity coordinates (0.397, 0.403)) after pressure treatment, the luminescent color gamut of [BPy]2CdBr4 changes from cyan-yellow light emission (CIE chromaticity coordinates (0.362, 0.399)) in the initial state to warm yellow light emission (CIE chromaticity coordinates (0.366, 0.422)) after pressure treatment, and the luminescent color gamut of [BPy]2CdCl4 changes from blue light emission (CIE chromaticity coordinates (0.153, 0.029)) in the initial state to orange-yellow light emission (CIE chromaticity coordinates (0.402, 0.413)) after pressure treatment. By intercepting the excellent high-pressure phase of metal halides, more valuable perovskite optoelectronic devices can be designed; by adjusting its performance through pressure, not only its optical performance is effectively improved, but also its light absorption ability is increased, which is of great significance for optimizing the performance of samples through high pressure; The materials used in the embodiments of the present invention are easy to prepare, stable under environmental conditions, emit light covering a relatively wide color gamut at normal temperature and pressure, and can adjust their optoelectronic properties and optimize the material performance through high-pressure treatment. The method of the embodiments of the present invention improves the photoluminescence intensity of the material under a fixed excitation light, and intercepts the excellent high-pressure phase of metal halides through pressure treatment. Description of the Drawings

[0013] Figure 1 It is the working principle diagram of the device adopted by a method for intercepting the high-pressure phase of Cd-based metal halides provided by an embodiment of the present invention; Figure 2 It is the fluorescence spectrogram of [BPy]2CdX4 (X is taken from I, Br, Cl) crystal samples provided by Embodiments 1-3 of the present invention under different pressures and after pressure treatment; Figure 3Fluorescence micrographs, CIE chromaticity diagrams, and chromaticity evolution trends of the [BPy]2CdX4 (X is taken from I, Br, Cl) crystal samples provided in Examples 1-3 of the present invention during the pressure application process and after the pressure treatment; Figure 4 Raman spectra of the [BPy]2CdX4 (X is taken from I, Br, Cl) crystal samples provided in Examples 1-3 of the present invention; Figure 5 Absorption spectra of the [BPy]2CdX4 (X is taken from I, Br, Cl) crystal samples provided in Example 4 of the present invention during the pressure application process; Figure 6 Bandgap comparison diagrams of the [BPy]2CdX4 (X is taken from I, Br, Cl) crystal samples provided in Example 4 of the present invention before and after the pressure treatment. Detailed implementation manners

[0014] In order to make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and 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.

[0015] The following describes the specific implementation of the present invention in detail with reference to specific embodiments.

[0016] Example 1. A method for intercepting the high-pressure phase of [BPy]2CdI4, adopting the structure as shown in Figure 1 and specifically including the following steps: (1) Using T301 stainless steel as the sealing metal gasket, first pre-press it to a thickness of 45 μm with a diamond anvil press with an anvil surface diameter of 400 μm, and then drill a hole with a diameter of 150 μm at the center of the pre-pressed position with a drill bit as the pressure cavity; (2) Put a [BPy]2CdI4 crystal sample with a diameter of 70 μm and a standard pressure substance ruby with a diameter of 10 μm into the pressure cavity, use mineral oil with a viscosity coefficient of 10 cst as the pressure transmission medium for cavity encapsulation, and pressurize the pressure from room temperature and normal pressure to 26 GPa.

[0017] Example 2. A method for intercepting the high-pressure phase of [BPy]2CdBr4, specifically including the following steps: (1) Using T301 stainless steel as the sealing metal gasket, first pre-press it to a thickness of 45 μm with a diamond anvil press with an anvil surface diameter of 400 μm, and then drill a hole with a diameter of 150 μm at the center of the pre-pressed position with a drill bit as the pressure cavity; (2) A [BPy]2CdBr4 crystal sample with a diameter of 70 μm and a standard pressure substance ruby with a diameter of 10 μm were placed into the pressure chamber together. Mineral oil with a viscosity coefficient of 10 cst was used as the pressure transmitting medium for chamber encapsulation, and the pressure was increased from room temperature and atmospheric pressure to 30 GPa.

[0018] Example 3: A method for intercepting the high-pressure phase of [BPy]2CdCl4, specifically including the following steps: (1) T301 stainless steel was used as the sealing metal gasket. First, a diamond anvil press with an anvil face diameter of 400 μm was used to pre-press it to a thickness of 45 μm, and then a drill bit was used to drill a hole with a diameter of 150 μm at the center of the pre-pressed position as the pressure chamber; (2) A [BPy]2CdCl4 crystal sample with a diameter of 70 μm and a standard pressure substance ruby with a diameter of 10 μm were placed into the pressure chamber together. Mineral oil with a viscosity coefficient of 10 cst was used as the pressure transmitting medium for chamber encapsulation, and the pressure was increased from room temperature and atmospheric pressure to 30 GPa.

[0019] Performance test: During the pressurization process, in-situ optical property testing of the sample was carried out simultaneously. Specifically, during the pressurization to 30 GPa, a 355 nm laser was used as the excitation light source, and an Ocean Optics QEPro spectrometer was used to collect the fluorescence signal of the sample. The results are as Figure 2 shown. For the metal halide perovskite samples of [BPy]2CdX4 (X is taken from I, Br, Cl), the fluorescence first increases and then decreases during the pressurization process. Due to the different halogens at the X position, the fluorescence peak positions show trends of first blue-shifting and then red-shifting and continuous red-shifting respectively; During the pressurization process, fluorescence micrographs were obtained as shown in Figure 3 a, 3b, 3c. In the figures, only the pressure points where the fluorescence of the corresponding halogen is basically quenched are shown. By plotting the CIE chromaticity coordinates against pressure through the fluorescence spectral curves at different pressures, the evolution trend is as shown in Figure 3 d, 3e, 3f. In the figures, the arrows indicate the color change trend, and the pentagrams indicate the CIE coordinate positions after pressure treatment; Figure 3 During the pressurization process, a 532 nm laser of a Raman spectrometer was used as the excitation light, and the low-wave number Raman spectra at normal pressure when the X position is different were compared. The results are as shown in shown; Figure 4 shown; There are no specific requirements for the material of the metal gasket and the anvil surface of the diamond anvil cell used in the embodiments of the present invention. As long as a pressure of 40 GPa can be applied, it is possible to achieve pressure-induced fluorescence enhancement of Cd-based metal halides while intercepting excellent high-pressure phases of metal halides. During the pressurization process, when X is I, Br, and Cl respectively, the emission intensities are enhanced by 8 times, 28 times, and 41 times respectively, enabling the luminescent color gamut of the material [BPy]2CdI4 to change from yellow light emission (CIE chromaticity coordinates (0.361, 0.400)) in the initial state to orange light emission (CIE chromaticity coordinates (0.397, 0.403)) after pressure treatment; [BPy]2CdBr4 changes from cyan-yellow light emission (CIE chromaticity coordinates (0.362, 0.399)) in the initial state to warm yellow light emission (CIE chromaticity coordinates (0.366, 0.422)) after pressure treatment; [BPy]2CdCl4 changes from weak blue light emission (CIE chromaticity coordinates (0.153, 0.029)) in the initial state to orange-yellow light emission (CIE chromaticity coordinates (0.402, 0.413)) after pressure treatment for effective tuning.

[0020] Example 4. A method for intercepting the high-pressure phase of Cd-based metal halides, specifically including the following steps: (1) Use T301 stainless steel as the sealing metal gasket. First, use a diamond anvil press with an anvil surface diameter of 400 μm to pre-press it to a thickness of 45 μm, and then drill a hole with a diameter of 150 μm at the center of the pre-pressed position as the pressure chamber; (2) Respectively place [BPy]2CdX4 (X is taken from I, Br, Cl) crystal samples with a diameter of 70 μm and ruby with a standard pressure substance with a diameter of 10 μm into the pressure chamber, use mineral oil with a viscosity coefficient of 10 cst as the pressure-transmitting medium for chamber encapsulation, and apply pressure respectively. Generally, the smaller the mass of the halogen atom, the stronger its pressure resistance. To compare the effects of different halogens on absorption under high pressure, when X is I, Br, and Cl respectively, the maximum pressures are applied to 30 GPa, 38 GPa, and 38 GPa; Measure the absorption spectrum of the [BPy]2CdX4 perovskite crystal sample under high pressure, as Figure 5 shown; Measure the absorption spectrum of the [BPy]2CdX4 perovskite crystal sample under high pressure, and obtain the optical band gap by extrapolating the intersection of the linear part of (αhν) 2 with hν in the Tauc plot, and compare the band gaps before and after pressure treatment, as Figure 6 shown.

[0021] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for intercepting the high-pressure phase of Cd-based metal halide, characterized in that, It includes the following steps: Pre-press a stainless steel metal sheet using a diamond anvil press, and drill a hole groove at the indentation as a pressure cavity; Put the Cd-based metal halide crystal into a pressure chamber, add mineral oil as the pressure-transmitting medium, and apply pressure. During the pressure application process, ruby is used as the pressure-calibrating substance. The chemical general formula of the Cd-based metal halide perovskite crystal is [BPy]2CdX4, where [BPy]2 is C 18 H 28 N2, and X is selected from I, Br, Cl; Regulate the properties of the Cd-based metal halide crystal through pressure. After slowly releasing the pressure, it exhibits an emission phenomenon different from the initial state, and the high-pressure phase of the Cd-based metal halide is intercepted.

2. The method for intercepting the high-pressure phase of Cd-based metal halide according to claim 1, wherein The diamond used in the diamond anvil press is a type IIa diamond.

3. The method for intercepting the high-pressure phase of Cd-based metal halide according to claim 1, characterized in that, The diameter of the hole groove is 150 μm, and the size of the Cd-based metal halide crystal is 50-100 μm in diameter.

4. The method for intercepting the high-pressure phase of Cd-based metal halide according to claim 1, wherein When X is I, Br, and Cl respectively, the pressure during the pressurization process is increased from normal temperature and pressure to 26 GPa, 30 GPa, and 30 GPa respectively.

5. The method for intercepting the high-pressure phase of Cd-based metal halide according to claim 1, characterized in that, When X is I, through pressure regulation, the emission color gamut changes from the yellow light emission CIE chromaticity coordinates (0.361, 0.400) in the initial state to the orange light emission CIE chromaticity coordinates (0.397, 0.403) after pressure treatment.

6. The method for intercepting the high-pressure phase of Cd-based metal halide according to claim 1, characterized in that, When X is Br, through pressure regulation, the emission color gamut changes from the cyan-yellow light emission CIE chromaticity coordinates (0.362, 0.399) in the initial state to the warm yellow light emission CIE chromaticity coordinates (0.366, 0.422) after pressure treatment.

7. The method for intercepting the high-pressure phase of Cd-based metal halide according to claim 1, characterized in that, When X is Cl, through pressure regulation, the emission color gamut changes from the blue light emission CIE chromaticity coordinates (0.153, 0.029) in the initial state to the orange-yellow light emission CIE chromaticity coordinates (0.402, 0.413) after pressure treatment.

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