Cs2WCl6 perovskite nano material and preparation method thereof

Abstract

A synthesis method of the nano material comprises the following steps: by taking a mixed solution of hydrochloric acid and ethanol as a solvent, adding oleic acid and octylamine, and stirring; continuously adding a hydrochloric acid solution containing cesium carbonate, and magnetically stirring; and washing the product with isopropanol, centrifuging, and drying to obtain the nano material. According to the method, the surface of the nano material is coated with the precursor through two organic ligands including oleic acid and octylamine, so that the nano material is good in dispersity and uniform in size, the method is easy and convenient to operate, the preparation time is short, high temperature is not needed, energy loss is effectively reduced, and an experimental basis is provided for controllable preparation and surface engineering of the nano material; the application in the fields of light-emitting devices, light detection and the like is promoted. And meanwhile, the prepared nano material can be directly applied to the scintillator, and an additional grinding step is not needed, so that the production efficiency is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nanomaterials, and particularly relates to a kind of perovskite nanomaterial and a preparation method thereof. BACKGROUND

[0002] Scintillation detectors can convert high-energy radiation or particles into low-energy photons (ultraviolet, visible or near-infrared) and are widely used in medical imaging, security inspection and high-energy physics. A typical scintillation detector is composed of a scintillator and a photodetector. In order to achieve high energy resolution, in addition to the requirement that the scintillator has high luminescent efficiency and excellent energy resolution, the photodetector needs to match the emission wavelength of the scintillator, so as to improve the detection efficiency. At present, the commonly used photodetectors include photomultiplier tubes (PMT), avalanche photodiodes (APD) and silicon photomultipliers (SiPM). At about 400 nm, the quantum efficiency of PMT can reach 30%, while APD and SiPM show higher quantum efficiency in the long-wavelength region (especially in the red to near-infrared band), and the quantum efficiency of APD often exceeds 80%. Therefore, the development of red or near-infrared emitting scintillator materials matching the photodetector has become an effective way to improve the scintillation performance.

[0003] The research on infrared-emitting perovskite materials mainly focuses on , lanthanide ion (Ce3+) doping and metal ion co-doped perovskites. However, due to poor stability in the environment, limiting its application; the emission of lanthanide ion (Ce3+) is low due to the parity-forbidden effect; and the energy transfer process of metal ions also restricts the luminescent performance. Recent studies have found that perovskite single crystals can achieve efficient near-infrared emission, covering the first (NIR-I) to second (NIR-II) biological window. More importantly, the emission band of perovskite is highly matched with silicon-based photodetectors, which provides a good foundation for the development of efficient scintillation detectors.

[0004] At present, the preparation method of perovskite single crystals, the hydrothermal method is more common, which can effectively synthesize perovskite single crystals. However, this method has the problems of long time consumption (usually 1-2 weeks are needed) and large-size single crystals as the product, which usually need to be further ground into powder for application and testing.

[0005] In the prior art, patent CA2998331A1 discloses a type of quaternary halide scintillator with an elpasolite-type structure, whose general formula is: ,For example (Commonly known as CLYC), it belongs to the vacancy-ordered double perovskite derived structure.

[0006] However, this patented technology has the following shortcomings in industrial applications:

[0007] High humidity sensitivity—The material contains lithium and rare earth activated impurities. This composition makes the material exhibit obvious hygroscopic properties, affecting its long-term stability and weather resistance, which is not conducive to conventional use and industrial deployment. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention provides a... Perovskite nanomaterials and their preparation methods.

[0009] This invention is achieved by providing a perovskite nanomaterial with the following chemical composition: It has a vacancy-ordered double perovskite structure with a size range of 1-5 nm.

[0010] Furthermore, the aforementioned It exhibits a monodisperse crystal morphology and a cubic phase lattice structure.

[0011] The present invention also provides a preparation A method for developing perovskite nanomaterials includes the following steps:

[0012] S1. In a mixed solution of hydrochloric acid and ethanol, add OA, OTA, and Stir at 80 °C until Completely dissolved;

[0013] S2, Add the substance containing [the substance] to the reaction solution of step S1. A hydrochloric acid solution was reacted with stirring at 80 °C to obtain... precipitation;

[0014] S3. The product from step S2 is washed with isopropanol and centrifuged, then dried in an oven at a temperature not exceeding 80 °C to obtain... Nanomaterials.

[0015] Furthermore, the volume ratio of hydrochloric acid to ethanol is 2:1.

[0016] Furthermore, the volume ratio of oleic acid to octylamine is 10:1.

[0017] Furthermore, the aforementioned The concentration of the hydrochloric acid solution was 1 mol / L, and the stirring time was 30 minutes.

[0018] The present invention also provides a method based on the method described in claim 1. An X-ray scintillation detector made of perovskite nanomaterials, comprising a scintillator layer and a photodetector, wherein the scintillator layer is composed of... It is composed of calcium ore nanomaterials, and the photodetector is a silicon-based photodetector.

[0019] Furthermore, the aforementioned Perovskite nanomaterials exhibit near-infrared emission in the 800-1250 nm wavelength range, and their emission wavelength matches the quantum efficiency curve of silicon-based photodetectors.

[0020] Furthermore, the photodetector is an avalanche photodiode or a silicon photomultiplier tube.

[0021] The present invention also provides an X-ray imaging system, which includes an X-ray source, a scintillation detector as described above, and an imaging display unit, for achieving high spatial resolution X-ray imaging.

[0022] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0023] This invention uses tungsten pentachloride (TPC) Using oleic acid (OA) and octylamine (OTA) as raw materials, the surface coating of perovskite nanomaterials was achieved through the synergistic effect of OA and OTA, resulting in... The nanoparticles exhibit good dispersion and uniform size. Compared to traditional hydrothermal methods, this approach is simpler to operate, has a shorter reaction time, and requires no high-temperature conditions, effectively reducing energy consumption and ensuring the stability and repeatability of the materials. The controllable preparation of nanomaterials provides new synthetic pathways.

[0024] By adopting Replaces tungsten tetrachloride (as previously reported) This not only changed the choice of precursors, but also significantly reduced the preparation cost. The market price is far lower than This makes the economic benefits of the invention more prominent in large-scale applications. This improvement overcomes the limitations of the original process route, ensures the feasibility and promotional value of material preparation, and demonstrates significant innovation and practicality.

[0025] The produced The advantages of nanomaterials in size and dispersibility make them directly applicable to the preparation of scintillators without further grinding, significantly improving the production efficiency compared to traditional single crystal materials. The advantages of material performance combined with low-cost synthesis methods make them have broad application prospects in the fields of light-emitting devices, light detectors and scintillators, and overall balance performance improvement and industrial feasibility.

[0026] In the prior art, The perovskite material usually presents a large size crystal morphology, and must be ground into powder to ensure uniform dispersion in polydimethylsiloxane (PDMS) when preparing a scintillator thin film. The present application directly prepares a perovskite material with good dispersibility by introducing a ligand engineering strategy, fundamentally avoids the grinding process, realizes process simplification and performance uniformization, and achieves unexpected technical effects for those skilled in the art. In addition, the present application uses cheap and easily available Instead of expensive As raw materials, it significantly reduces the preparation cost while ensuring material performance, achieving comprehensive effects that those skilled in the art have not anticipated. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The perovskite material obtained when no organic ligand coating is added for the embodiments of the present application;

[0028] Figure 2 The perovskite material obtained when coated with 5:1 organic ligand for the embodiments of the present application;

[0029] Figure 3 The perovskite material obtained when coated with 10:1 organic ligand for the embodiments of the present application;

[0030] Figure 4 The perovskite material obtained when coated with 15:1 organic ligand for the embodiments of the present application;

[0031] Figure 5 The XRD spectrum provided for the embodiments of the present application: (a) The standard spectrum; (b) the spectrum of the synthesized Without adding OA and OTA; (c) the spectrum of the synthesized OA and OTA in a ratio of 5:1; (d) the spectrum of the synthesized OA and OTA in a ratio of 10:1; (e) the spectrum of the synthesized OA and OTA in a ratio of 15:1.​​​​

[0032] Figure 6 It is shown that The photoluminescence (PL) spectrum of the nanomaterial. DETAILED DESCRIPTION

[0033] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application.

[0034] In existing industrial applications, traditional scintillators mainly emit in the ultraviolet and visible light bands, and their emission peak positions do not completely match the response of silicon-based photodetectors, which limits the detection efficiency and imaging sensitivity. In particular, in medical X-ray imaging and security systems, insufficient energy utilization will cause the demand for radiation dose to increase, thereby causing safety hazards to patients or users. Therefore, there is an urgent need for a new type of scintillating material that can achieve strong emission in the near-infrared region and match the high quantum efficiency interval of silicon-based detectors, in order to reduce the dose and improve the imaging resolution.

[0035] The vacancy-ordered double perovskite material provides new possibilities in this context. It exhibits broadband emission in the 800-1250 nm band, covering the high response region of silicon photodiodes and silicon photomultipliers. This means thatAs a scintillator, it can achieve high photon collection efficiency in radiation detectors, solving the limitations of traditional scintillating materials in spectral matching and creating conditions for reducing system noise and improving imaging signal-to-noise ratio. In terms of material physics mechanisms,

[0036] The near-infrared emission of the material is derived from self-trapped excitons (STEs). When X-ray photons enter the material, their high energy is first localized by tungsten-chlorine octahedra, resulting in strong electron-phonon coupling. This coupling causes lattice distortion, which in turn forms a self-trapped exciton state, and releases near-infrared photons through radiative recombination. The large Stokes shift (about 560 nm) of this process effectively avoids self-absorption, allowing the emitted photons to be efficiently transmitted to the photodetector. In industrial application scenarios, this working principle brings significant advantages. For example, in X-ray CT devices,

[0037] The scintillation layer can be directly integrated with the silicon photomultiplier tube, reducing the need for wavelength conversion or matching layers and simplifying system design. Simultaneously, due to its emission lifetime on the order of microseconds, it can maintain signal integrity under rapid pulse radiation conditions, meeting the requirements of high-speed imaging and high-count-rate detection. This is of great significance for real-time imaging in security inspection equipment and dynamic image acquisition in medical diagnosis.

[0038] In terms of material preparation technology, this invention proposes an improved co-precipitation method combined with ligand engineering, which significantly shortens the preparation time. The synthesis cycle is shortened, and the stable and controllable nanoscale size (1-5 nm) is ensured. This preparation advantage not only improves the efficiency of mass production of materials, but also provides process compatibility for film formation, composite scintillator preparation, and flexible detector construction. Compared with the hydrothermal method, which requires several weeks to prepare large-size single crystals, this method can quickly obtain high-purity nanoparticles, reducing the cost barrier for industrial applications.

[0039] final, Perovskite nanomaterials, through spectral matching, long-lifetime self-trapped exciton emission, high-purity nanoscale fabrication, and excellent device integration, systematically solve the problems of insufficient efficiency, high cost, and poor system matching of existing scintillation materials in the industrial application of X-ray imaging. Their working principle and technological advantages together lay the foundation for broad application prospects in fields such as medical imaging, public security inspection, and high-energy physics experiments, providing core material support for next-generation high-resolution X-ray imaging systems.

[0040] This invention provides a Perovskite nanomaterials have the following chemical composition: The size is 1-5 nm.

[0041] This invention provides a This perovskite nanomaterial exhibits a typical vacancy-ordered double perovskite structure and has the following chemical formula: The particle size is controlled within the range of 1-5 nm, exhibiting a monodisperse nanocrystal morphology.

[0042] In terms of preparation, this embodiment employs an improved co-precipitation process, using cesium carbonate (CeS2 carbonate) as the precursor. ) and tungsten pentachloride ( The main precursor is oleic acid (OA) and octylamine (OTA). First, using a mixed solution of hydrochloric acid (HCl) and ethanol as a solvent, oleic acid (OA) and octylamine (OTA) are added. Stir at 80 °C until... The precursor was completely dissolved. Then, a mixture containing... The HCl solution was stirred magnetically at 80 °C for 30 minutes to ensure complete reaction. Finally, the obtained product was washed with isopropanol, centrifuged, and dried to obtain the final product. Nanomaterials.

[0043] The nanocrystals exhibit a high-purity cubic phase structure. Characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed that their composition and structure were consistent with expectations, and that the particle size was stably controlled.

[0044] because Nanocrystals exhibit broadband strong emission in the near-infrared band (approximately 800-1250 nm), which highly matches the high quantum efficiency band of silicon-based photodetectors, demonstrating significant application potential in X-ray imaging, near-infrared biological imaging, and high-energy radiation detection. This is especially true for nanoscale nanocrystals. It not only has higher dispersibility and adaptability to film preparation, but can also be combined with polymer or inorganic matrices to construct high-sensitivity scintillation detectors, providing key material support for achieving high spatial resolution imaging.

[0045] Figure 6 Showing The photoluminescence (PL) spectrum of the nanomaterial is shown, with wavelength (nm) on the x-axis and emission intensity (au) on the y-axis. The graph reveals a distinct emission peak in the near-infrared region, with the main peak located around 900 nm, indicating that the material can generate a strong emission signal in this region. The overall curve exhibits a rapid rise at the peak followed by a gradual decay.

[0046] In the spectral range of 800-1250 nm, The emission intensity of the nanomaterial rapidly increases in the short wavelength region, reaching a maximum near 900 nm. Thereafter, the emission intensity gradually decreases with increasing wavelength, exhibiting a relatively broad tail extension. This spectral characteristic indicates that the material possesses broadband emission properties, capable of covering a large area of ​​the near-infrared spectrum, making it suitable for applications related to optical imaging and infrared detection.

[0047] Example 1: Without adding organic ligands Synthesis of nanomaterials

[0048] Using a mixture of 10 mL hydrochloric acid and 5 mL ethanol as a solvent, add 1 mmol Heat and stir at 80°C for 2 hours until... The precursor was completely dissolved. Next, 1 ml of solution containing 1 mmol was added. After adding HCl solution, the mixture was magnetically stirred at 80 °C for 30 min to ensure complete reaction. The prepared product was washed with isopropanol and centrifuged three times, and finally dried in an oven at 60 °C. Figure 1 It was observed that, without organic ligand coating, the obtained The perovskite material appears serious agglomeration, and the dispersibility is very poor.

[0049] Example 2: OA:OTA = 5:1 ratio Synthesis of nanomaterials

[0050] In the case of introducing organic ligand, 10 mL of mixed solution of hydrochloric acid and 5 mL of ethanol as solvent, adding OA and OTA with a volume ratio of 5:1, and adding 1 mmol , heating and stirring at 80 °C for 2 hours until the precursor is completely dissolved. Then, after adding 1 ml of 1 mmol HCl solution, the above mixture is magnetically stirred at 80 °C for 30 min to ensure complete reaction. The prepared product is washed by isopropanol and centrifuged three times, and finally dried in a 60 °C oven. From Figure 2 It can be seen that, under the condition of 5:1 ratio, although the agglomeration phenomenon is alleviated, the relative excess of OTA will form excessive coating on the particle surface, so that the particle is limited and the dispersibility is reduced.

[0051] Example 3: OA:OTA = 10:1 ratio Synthesis of nanomaterials

[0052] When the OA:OTA ratio is further adjusted to 10:1, 10 mL of mixed solution of hydrochloric acid and 5 mL of ethanol as solvent, OA and OTA with a volume ratio of 10:1 are added, and 1 mmol , heating and stirring at 80 °C for 2 hours until the precursor is completely dissolved. Then, after adding 1 ml of 1 mmol HCl solution, the above mixture is magnetically stirred at 80 °C for 30 min to ensure complete reaction. The prepared product is washed by isopropanol and centrifuged three times, and finally dried in a 60 °C oven. From Figure 3 It can be seen that, under the condition of 5:1 ratio, although the agglomeration phenomenon is alleviated, the relative excess of OTA will form excessive coating on the particle surface, so that the particle is limited and the dispersibility is reduced. The size of the obtained nanomaterial is about 1-5 nm, and the dispersibility is good. This shows that 10:1 is a better ratio to obtain high-quality nanomaterials.

[0053] Example 4: OA:OTA = 15:1 ratio Synthesis of nanomaterials

[0054] 10 mL of mixed solution of hydrochloric acid and 5 mL of ethanol as solvent, OA and OTA with a volume ratio of 15:1 are added, and 1 mmol , heating and stirring at 80 °C for 2 hours until the precursor is completely dissolved. Then, after adding 1 ml of 1 mmol After adding HCl solution, the mixture was magnetically stirred at 80 °C for 30 min to ensure complete reaction. The prepared product was washed with isopropanol and centrifuged three times, and finally dried in an oven at 60 °C. Figure 4 It was observed that, compared to the 10:1 condition, the 15:1 ligand ratio contained relatively too little OTA, leading to a ligand imbalance in the system, thus... The dispersibility of perovskite materials is significantly reduced.

[0055] Figure 5 XRD patterns provided for embodiments of the present invention: (a) (a) Standard spectrum; (b) Synthesized without the addition of OA and OTA. Spectrum; (c) Synthesized when OA and OTA are in a 5:1 ratio Spectrum; (d) Synthesized when OA and OTA are in a 10:1 ratio Spectrum; (e) Synthesized when OA and OTA are in a 15:1 ratio Spectrum.

[0056] This invention adjusts the ratio of OA to OTA to Coating the surface of nanocrystals enables effective control over particle size and dispersibility. Figure 3 The results show that when the ratio of OA to OTA is 10:1, the resulting particles exhibit good dispersion and uniform size distribution, avoiding agglomeration and demonstrating excellent nanoscale controllability.

[0057] like Figure 5 The XRD patterns shown indicate that, under conditions of no organic ligand addition and with the addition of a certain proportion of organic ligand, the obtained... The XRD pattern (curve be) of the nanomaterial is highly consistent with the standard pattern (curve a), proving that products with pure crystal structure and excellent crystallinity can be obtained under the above conditions. Combined with the aforementioned TEM characterization results, it can be further confirmed that the organic ligand plays a key role in the crystal morphology regulation process, but does not affect the synthesis of the material. Therefore, this invention achieves high-quality synthesis using low-cost precursors. The controllable synthesis of nanomaterials, which exhibit significant advantages in particle size uniformity, dispersibility and crystallinity, provides a high-quality material basis for their application in fields such as optics and scintillator devices.

[0058] 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 modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A perovskite nanomaterial, the chemical composition of which is as follows: It has a vacancy-ordered double perovskite structure with a particle size ranging from 1 to 5 nanometers.

2. The perovskite nanomaterial according to claim 1, characterized in that, The Nanomaterials exhibit monodisperse crystal morphology and a cubic phase lattice structure.

3. The perovskite nanomaterial according to claim 1, characterized in that, The Nanomaterials exhibit near-infrared emission properties in the wavelength range of 800 to 1250 nanometers.

4. A method for preparing the product according to claim 1 The method for perovskite nanomaterials is characterized by, Includes the following steps: Step one: Add oleic acid, octylamine, and... to the mixed solution of hydrochloric acid and ethanol. ,exist Stir until Completely dissolved; Step two, add a hydrochloric acid solution containing cesium carbonate to the reaction solution from step one. The reaction is stirred to produce precipitation; Step 3: The product obtained in Step 2 is washed with isopropanol and centrifuged. The centrifuge solution is then subjected to a process with a viscosity not exceeding [a certain value]. Drying in an oven to obtain Nanomaterials.

5. The method according to claim 4, characterized in that, The volume ratio of hydrochloric acid to ethanol is 2:

1.

6. The method according to claim 4, characterized in that, The volume ratio of oleic acid to octylamine is 10:

1.

7. The method according to claim 4, characterized in that, The concentration of the cesium carbonate hydrochloric acid solution is The stirring time is 30 minutes.

8. An X-ray scintillation detector, characterized in that, It includes a scintillator layer and a photodetector, wherein the scintillator layer is as described in claim 1. It is composed of perovskite nanomaterials, and the photodetector is a silicon-based photodetector.

9. The X-ray scintillation detector according to claim 8, characterized in that, The Perovskite nanomaterials exhibit emission peaks in the near-infrared band of 800 to 1250 nm, and their emission bands match the quantum efficiency curves of silicon-based photodetectors.

10. The X-ray scintillation detector according to claim 8, characterized in that, The photodetector is an avalanche photodiode or a silicon photomultiplier tube, and it is combined with the imaging display unit to form an X-ray imaging system to achieve high spatial resolution X-ray imaging.

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