A main group element ion-doped zero-dimensional metal halide fluorescent sensing material, a preparation method therefor, and an application thereof

Abstract

The application provides a main group element ion doped zero-dimensional metal halide fluorescent sensing material and a preparation method and application thereof, and belongs to the technical field of fluorescent sensing materials. The main group element ion doped zero-dimensional metal halide microcrystal is synthesized by a solvothermal method, the strong dependence of two thermal coupling energy levels of the main group element ion on temperature is utilized, the main group element ion doped zero-dimensional metal halide shows an obvious temperature dependence evolution trend of fluorescence lifetime and fluorescence intensity at low temperature, and dual-mode (fluorescence intensity ratio / fluorescence lifetime) high-sensitivity temperature detection in a liquid helium temperature region can be realized. The synthesis method is simple in process and easy to control in synthesis conditions, the obtained material shows extremely high relative sensitivity in the liquid helium temperature region, has high practical application value, can be used as a novel optical temperature sensing material, and can be used for temperature detection in various extreme temperature regions.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to the preparation of a main group element ion-doped zero-dimensional metal halide fluorescent sensing material and its application in temperature detection in extreme low-temperature regions, and belongs to the field of fluorescent sensing materials technology. Background Technology

[0002] Temperature is one of the most important physical parameters in natural processes. Accurate temperature sensing, especially in extreme cryogenic environments such as liquid helium (4.2 K) and liquid nitrogen (77 K), is of profound significance for advancing basic scientific research and breakthroughs in cutting-edge technologies. Among numerous temperature measurement techniques, fluorescence-based sensing is favored due to its remote operation, high spatial resolution, and rapid response. Fluorescence intensity ratio (FIR) and fluorescence lifetime (FL) are two main temperature sensing parameters, with fluorescence lifetime possessing unique advantages due to its susceptibility to excitation light fluctuations or optical path losses. However, traditional fluorescence lifetime thermometers typically rely on thermal activation through a non-radiative relaxation process, making them effective only at higher temperatures. In the low-temperature range, particularly below 77 K, the thermal activation effect is significantly suppressed, leading to a substantial reduction in sensitivity and reliability in the cryogenic region, thus affecting the accuracy of cryogenic temperature detection.

[0003] In the search for alternatives to lead halide perovskites, environmentally friendly and stable lead-free metal halides (MHs) have emerged as excellent luminescent materials for next-generation light-harvesting and light-emitting applications. Through ion doping, a series of highly efficient lead-free metal halide luminescent materials with superior optical performance have been developed. Due to their high sensitivity, solution processability, and ease of device integration, these materials are also considered promising candidates for temperature measurement using fluorescence intensity ratio or fluorescence lifetime, and are gradually standing out among numerous optical thermometric materials. However, most current research focuses on temperature ranges above 77 K, and performance in the low-temperature region remains limited by low sensitivity and unclear mechanisms. For example, doping with main group element ions (such as Sn...) 2+ Sb 3+ Te 4+ Metal halides of main group elements have been applied to high-sensitivity temperature measurements in the range of 40–170 K. However, the photoluminescence mechanism of these main group element-doped systems remains controversial, often simply attributed to self-trapped exciton emission, highlighting the urgent need for a more fundamental and clearer understanding of the mechanism. Therefore, there is a pressing need to develop a novel temperature sensing technology that can achieve high sensitivity at extreme low temperatures and overcome the limitations of traditional fluorescence thermometers that rely on non-radiative relaxation, in order to meet the needs of temperature detection in extreme low-temperature regions. Summary of the Invention

[0004] To address the aforementioned technical challenges, this invention provides a method for preparing a zero-dimensional metal halide fluorescent sensing material doped with main group element ions and for its application in temperature detection in extreme low-temperature regions. This material exhibits both characteristic luminescence and high temperature sensitivity. By detecting the fluorescence lifetime and luminescence intensity of this material, a dual-mode (fluorescence intensity ratio / fluorescence lifetime) thermometer can be used for temperature detection in extreme low-temperature regions.

[0005] The present invention adopts the following technical solution: A zero-dimensional metal halide luminescent material doped with main group element ions, wherein the main group element ions serve as the luminescent centers, and the main group element is selected from Tl. + Sn 2+ Sb 3+ Bi 3+ Te 4+ Se 4+ Any one of them.

[0006] This invention provides a method for preparing main group element ion-doped zero-dimensional metal halide luminescent materials, comprising the following steps: S1. Weigh out the metal precursor dissolved in the solvent; the doped ionic compound is selected from Tl. + Sn 2+ Sb 3+ Bi 3+ Te 4 + or Se 4+ One of the following: oxide, halide, carbonate, nitrate, or acetate; S2. Transfer the solid mixed solution obtained in step S1 to a closed reaction vessel and carry out a solvothermal reaction under certain temperature conditions. S3. After the reaction is complete, cool to room temperature to obtain a zero-dimensional metal halide luminescent material doped with main group element ions.

[0007] According to the present invention, in step S1, the solvent is one of hydrochloric acid, acetic acid, nitric acid, and methanol, and the dissolution process is magnetic stirring for 20-30 min.

[0008] According to the present invention, in step S2, the temperature needs to be rapidly increased to the reaction temperature within 12-20 minutes, with a heating rate of 5-8 °C / h. -1 .

[0009] According to the present invention, in step S2, the reaction temperature is 150-200 °C; the reaction time is 12-24 h.

[0010] According to the present invention, step S3 employs stepwise cooling. The cooling rate is 0.5-1 °C / h between 150-200 °C. -1 Cooling from 150 ℃ to room temperature at a rate of 3-5 ℃ / h-1 .

[0011] According to the present invention, step S3 further includes the following step: after the reaction vessel is cooled to room temperature, the reaction liquid is separated and washed.

[0012] According to an embodiment of the present invention, the preparation method further includes washing the solid product obtained by solid-liquid separation to remove residual solution and unreacted precursors on the surface of the solid product.

[0013] Preferably, the washing solvent is an organic solvent. For example, the washing solvent can be ethanol or isopropanol. Ethanol is preferred. Furthermore, the washing method can be filtration washing or centrifugal washing.

[0014] According to one embodiment of the present invention, the preparation method further includes drying the washed solid product to obtain a main group element ion-doped zero-dimensional metal halide luminescent material. For example, the drying temperature is 30-80 °C, preferably 50-80 °C, with examples being 50 °C, 60 °C, 70 °C, and 80 °C.

[0015] The present invention also provides the above-mentioned main group element ion-doped zero-dimensional metal halide luminescent materials for use in the field of low temperature detection such as liquid helium and liquid nitrogen. The temperature detection can be as low as 4 K. High-sensitivity low temperature sensing can be achieved by measuring the fluorescence lifetime and fluorescence intensity ratio with temperature at extremely low temperatures.

[0016] Furthermore, the temperature range for low-temperature testing is 4 K-70 K.

[0017] The beneficial effects of this invention are as follows: 1. The reaction raw materials involved in this invention can be purchased directly from reagent companies without further purification.

[0018] 2. The main group element ion-doped zero-dimensional metal halide luminescent material synthesized using this invention exhibits high sensitivity and a wide detection range, demonstrating excellent temperature detection performance. At 10 K, this material can achieve a temperature sensitivity as high as 8.5% K₀. -1 The material exhibits high relative sensitivity and good practicality. It demonstrates high sensitivity and a wide temperature detection range at low temperatures, meeting the diverse application requirements for low-temperature detection. Attached Figure Description

[0019] Figure 1 For Te 4+ A schematic diagram of the structure of the Cs2ScCl5·H2O doped sample and a photograph of the luminescent material under ultraviolet light.

[0020] Figure 2 Different concentrations of Te in Examples 1-34+ Doped Cs₂ScCl₅·H₂O: x %Te 4+ ( x X-ray powder diffraction patterns of the samples with doped values ​​of 0.1, 0.4, and 1.0 and the undoped sample.

[0021] Figure 3 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ X-ray photoelectron spectra of the sample and the undoped sample.

[0022] Figure 4 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ Raman spectra of the sample and the undoped sample.

[0023] Figure 5 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ Excitation and emission spectra of the sample; solid line: emission spectrum (excitation wavelength 375 nm); dashed line: excitation spectrum (emission wavelength 652 nm).

[0024] Figure 6 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ Thermogravimetric spectra of the sample and the undoped sample.

[0025] Figure 7 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ Photostress resistance spectrum of the sample.

[0026] Figure 8 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ X-ray powder diffraction pattern of the sample after it has been exposed to air for three months.

[0027] Figure 9 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ The spectrum of luminescence intensity changes of the sample after it has been exposed to air for three months.

[0028] Figure 10 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ Temperature-dependent spectra of the sample.

[0029] Figure 11 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ The fluorescence lifetime of the sample changes with temperature.

[0030] Figure 12 The Cs₂ScCl₅·H₂O obtained in Example 2: 0.4%Te 4+ The relative sensitivity diagram of the low-temperature sensing of the sample.

[0031] Figure 13 The Cs₂ScCl₅·H₂O obtained in Example 1: 0.4%Te 4+ A schematic diagram of the sample used as a dual-mode (fluorescence intensity ratio / fluorescence lifetime) thermometer for extreme low-temperature sensing. Detailed Implementation

[0032] The present invention will be described in detail below through specific embodiments. However, those skilled in the art will understand that the following embodiments are not intended to limit the scope of protection of the present invention, and any improvements and changes made on the basis of the present invention are within the scope of protection of the present invention.

[0033] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0034] The instrument and equipment are shown below: The instrument used for X-ray powder diffraction of the product in this embodiment of the invention is a MiniFlex600, manufactured by Rigaku, with a copper target radiation wavelength of [wavelength missing]. λ = 0.154187 nm.

[0035] The instrument used for X-ray energy dispersive spectroscopy analysis of the product in this embodiment of the invention is an ESCALAB 250Xi, manufactured by Thermo Fisher.

[0036] The instrument used for Raman spectroscopy analysis of the product in this embodiment of the invention is a LabRAM HR Evolution, manufactured by Horiba Jobin Yvon.

[0037] The instrument used for emission spectral characterization of the product in this embodiment of the invention is an FLS980 manufactured by Edinburgh. The excitation source is a xenon lamp with an excitation wavelength of 375 nm and a monitoring wavelength of 652 nm. Example 1

[0038] This embodiment provides a chemical formula Cs2ScCl5·H2O: 0.1%Te 4+ The specific preparation method for group-group element ion-doped zero-dimensional metal halide luminescent materials is as follows: S1. Weigh 0.25 mmol of scandium oxide (Sc2O3) powder, 0.002 mmol of tellurium chloride (TeCl4) powder and 1 mmol of cesium chloride (CsCl) powder at room temperature and add them to 25 mL of polytetrafluoroethylene liner. Then add 2 mL of hydrochloric acid (37wt%) and mix well.

[0039] S2. Place the inner liner in the stainless steel reactor and put it in an oven. Rapidly heat the oven to 180 ℃ (20 min) and maintain the temperature for 12 h, controlling the oven program at 1 ℃ / h. -1 Cooled to 150 °C at a rate of [missing information], then at 3 °C / h. -1 Cooled to room temperature at a rate of [missing information].

[0040] S3. After the reaction is complete, the product is washed with ethanol to obtain Cs₂ScCl₅·H₂O: 0.1%Te 4+ Luminescent materials. Example 2

[0041] This embodiment provides a chemical formula Cs2ScCl5·H2O: 0.4%Te 4+ The specific preparation method for group-group element ion-doped zero-dimensional metal halide luminescent materials is as follows: S1. Weigh 0.25 mmol of scandium oxide (Sc2O3) powder, 0.008 mmol of tellurium chloride (TeCl4) powder and 1 mmol of cesium chloride (CsCl) powder at room temperature and add them to 25 mL of polytetrafluoroethylene liner. Then add 2 mL of hydrochloric acid (37wt%) and mix well.

[0042] S2. Place the inner liner in the stainless steel reactor and put it in an oven. Rapidly heat the oven to 180 ℃ (20 min) and maintain the temperature for 12 h, controlling the oven program at 1 ℃ / h. -1 Cooled to 150 °C at a rate of [missing information], then at 3 °C / h. -1 Cooled to room temperature at a rate of [missing information].

[0043] S3. After the reaction is complete, the product is washed with ethanol to obtain Cs₂ScCl₅·H₂O: 0.4%Te 4+ Luminescent materials. Example 3

[0044] This embodiment provides a chemical formula Cs2ScCl5·H2O: 1.0%Te 4+ The specific preparation method for group-group element ion-doped zero-dimensional metal halide luminescent materials is as follows: S1. Weigh 0.25 mmol of scandium oxide (Sc2O3) powder, 0.02 mmol of tellurium chloride (TeCl4) powder and 1 mmol of cesium chloride (CsCl) powder at room temperature and add them to 25 mL of polytetrafluoroethylene liner. Then add 2 mL of hydrochloric acid (37wt%) and mix well.

[0045] S2. Place the inner liner in the stainless steel reactor and put it in an oven. Rapidly heat the oven to 180 ℃ (20 min) and maintain the temperature for 12 h, controlling the oven program at 1 ℃ / h. -1 Cooled to 150 °C at a rate of [missing information], then at 3 °C / h. -1 Cooled to room temperature at a rate of [missing information].

[0046] S3. After the reaction is complete, the product is washed with ethanol to obtain Cs₂ScCl₅·H₂O: 1.0%Te 4+ Luminescent materials. Example 4

[0047] This embodiment provides a chemical formula Cs2ScCl5·H2O: 0.4%Te 4+ The specific preparation method for group-group element ion-doped zero-dimensional metal halide luminescent materials is as follows: S1. Weigh 0.25 mmol of scandium oxide (Sc2O3) powder, 0.008 mmol of tellurium chloride (TeCl4) powder and 1 mmol of cesium chloride (CsCl) powder at room temperature and add them to 25 mL of polytetrafluoroethylene liner. Then add 2 mL of hydrochloric acid (37wt%) and mix well.

[0048] S2. Place the inner liner in the stainless steel reactor and put it in an oven. Rapidly heat the oven to 180 ℃ (20 min) and maintain the temperature for 16 h, controlling the oven program at 1 ℃ / h. -1 Cooled to 150 °C at a rate of [missing information], then at 3 °C / h. -1 Cooled to room temperature at a rate of [missing information].

[0049] S3. After the reaction is complete, the product is washed with ethanol to obtain Cs₂ScCl₅·H₂O: 0.4%Te 4+ Luminescent materials. Example 5

[0050] This embodiment provides a chemical formula Cs2ScCl5·H2O: 0.4%Te 4+ The specific preparation method for group-group element ion-doped zero-dimensional metal halide luminescent materials is as follows: S1. Weigh 0.25 mmol of scandium oxide (Sc2O3) powder, 0.008 mmol of tellurium chloride (TeCl4) powder and 1 mmol of cesium chloride (CsCl) powder at room temperature and add them to 25 mL of polytetrafluoroethylene liner. Then add 2 mL of hydrochloric acid (37wt%) and mix well.

[0051] S2. Place the inner liner in the stainless steel reactor and put it in the oven. Rapidly heat to 160 ℃ (15 min) and maintain for 12 h, controlling the oven program at 1 ℃ / h. -1 Cooled to 150 °C at a rate of [missing information], then at 3 °C / h. -1 Cooled to room temperature at a rate of [missing information].

[0052] S3. After the reaction is complete, the product is washed with ethanol to obtain Cs₂ScCl₅·H₂O: 0.4%Te 4+ Luminescent materials. Example 6

[0053] This embodiment provides a chemical formula Cs2ScCl5·H2O: 0.4%Te 4+ The specific preparation method for group-group element ion-doped zero-dimensional metal halide luminescent materials is as follows: S1. Weigh 0.25 mmol of scandium oxide (Sc2O3) powder, 0.008 mmol of tellurium chloride (TeCl4) powder and 1 mmol of cesium chloride (CsCl) powder at room temperature and add them to 25 mL of polytetrafluoroethylene liner. Then add 2 mL of hydrochloric acid (37wt%) and mix well.

[0054] S2. Place the inner liner in the stainless steel reactor and put it in the oven. Rapidly heat to 160 ℃ (15 min) and maintain for 16 h, controlling the oven program at 1 ℃ / h. -1 Cooled to 150 °C at a rate of [missing information], then at 3 °C / h. -1 Cooled to room temperature at a rate of [missing information].

[0055] S3. After the reaction is complete, the product is washed with ethanol to obtain Cs₂ScCl₅·H₂O: 0.4%Te 4+ Luminescent materials.

[0056] Performance testing

[0057] Different concentrations of Te were prepared using the methods described in Examples 1-3 above. 4+ The structure and optical properties of the doped Cs₂ScCl₅·H₂O luminescent material were characterized and compared with those of the undoped sample. The results are as follows: The Te prepared in Example 1 4+A schematic diagram of the structure of the Cs₂ScCl₅·H₂O-doped luminescent material and a photograph of the luminescence of the material under ultraviolet light are shown below. Figure 1 As shown.

[0058] like Figure 2 As shown, different Te 4+ Doping concentration Cs2ScCl5·H2O: x %Te 4+ The X-ray powder diffraction pattern shows that the diffraction peaks of the prepared samples all correspond one-to-one with the standard PDF card of Cs2ScCl5·H2O, indicating that the synthesized samples are all pure phases. With the development of Te... 4+ As the doping concentration increases, the diffraction peaks of powder XRD shift to lower angles, indicating that the larger ionic radius of Te... 4+ (0.097 nm) replaced the Sc with a smaller ionic radius. 3+ (0.081 nm) causes lattice expansion.

[0059] like Figure 3 As shown, X-ray photoelectron spectroscopy indicates that Te 4+ The doped sample contained Cs, Sc, Cl, and Te elements, all in their corresponding valence states, confirming the presence of Te. 4+ Successful doping.

[0060] like Figure 4 As shown, Raman spectroscopy reveals Te 4+ The presence of Sc-Cl and Te-Cl bonds in the doped sample confirms that Te... 4 + Replaced the octahedral Sc 3+ The location.

[0061] like Figure 5 As shown, under 375 nm excitation, the sample has an emission peak at 652 nm, and its down-transfer photoluminescence quantum yield was measured to be 28.6%.

[0062] like Figure 6 As shown, the thermogravimetric analysis spectrum indicates that the sample can retain 95% of its original mass at a temperature of 334 °C, demonstrating its good thermal stability.

[0063] like Figure 7 As shown, after continuous irradiation with 375 nm ultraviolet light for 90 min, the fluorescence emission intensity of the prepared sample hardly decreased, indicating that the sample has excellent photoresistance.

[0064] like Figure 8 As shown, the sample did not undergo a phase change after being placed in air for 3 months, indicating that it has good air stability.

[0065] like Figure 9 As shown, after the sample was placed in the air for 3 months, its fluorescence emission intensity could still maintain 91.0% of the initial intensity, indicating that it has good photostability.

[0066] like Figure 10 As shown, as the temperature decreases from 300 K to 4 K, the emission peak of the sample gradually blue-shifts. At 4 K, the emission peak exhibits a bimodal emission of high energy (600 nm) and low energy (670 nm). The emission peak intensity remains almost constant in the temperature range of 4-70 K. As the temperature exceeds 70 K, the intensity of the high-energy band gradually decreases, while the low-energy band shows the opposite trend. Furthermore, when the temperature exceeds 220 K, the high-energy band completely disappears, resulting in emission dominated by the low-energy band at room temperature. The change in the fluorescence intensity ratio of the high-energy to low-energy bands with temperature provides a basis for temperature sensing.

[0067] like Figure 11 As shown, as the temperature increased from 4 K to 70 K, the fluorescence lifetime of the sample decreased sharply from 145 μs to 8.9 μs, only about 6.1% of the initial value, exhibiting strong temperature dependence. This significant lifetime change endows the system with excellent low-temperature discrimination capabilities, making it a promising candidate for applications in the field of cryogenic sensing.

[0068] according to Figure 10 and Figure 11 The results were fitted to obtain the relative sensitivity curve of the temperature sensor for the sample. like Figure 12 As shown, the maximum relative sensitivity is 8.5% of K at 10 K. -1 This indicates that the sample has excellent low-temperature sensing performance.

[0069] like Figure 13 As shown, due to Te 4+ The characteristic emission at low temperatures and the strong temperature dependence of fluorescence lifetime, through temperature-dependent spectral correction, make the sample a promising candidate for dual-mode (fluorescence intensity ratio / fluorescence lifetime) thermometer applications.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. All equivalent substitutions, modifications, or improvements made by those skilled in the art without departing from the technical concept and spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A zero-dimensional metal halide luminescent material doped with main group element ions, characterized in that, Main group element ions serve as luminescent centers, where the main group elements are selected from Tl. + Sn 2+ Sb 3+ Bi 3+ Te 4+ Se 4+ Any one of them.

2. A method for preparing a main group element ion-doped zero-dimensional metal halide luminescent material as described in claim 1, characterized in that, Includes the following steps: S1, a metal precursor is weighed and dissolved in a solvent, the doped ion compound is selected from one of the oxides, halides, carbonates, nitrates or acetates of Tl + , Sn 2+ , Sb 3+ , Bi 3+ , Te 4+ or Se 4+ . S2. Transfer the solid mixed solution obtained in step S1 to a closed reaction vessel and carry out a solvothermal reaction under certain temperature conditions. S3. After the reaction is complete, cool to room temperature to obtain a zero-dimensional metal halide luminescent material doped with main group element ions.

3. The preparation method according to claim 2, characterized in that, In step S1, the solvent is one of hydrochloric acid, acetic acid, nitric acid, or methanol, and the dissolution process involves magnetic stirring for 20-30 minutes.

4. The preparation method according to claim 2, characterized in that, In step S2, the temperature needs to be rapidly increased to the reaction temperature within 12-20 minutes, with a heating rate of 5-8 °C / h. -1 .

5. The preparation method according to claim 2, characterized in that, In step S2, the reaction temperature is 150-200℃; the reaction time is 12-24 h.

6. The preparation method according to claim 2, characterized in that, In step S3, stepwise cooling is employed: the cooling rate is 0.5-1 °C / h between 150-200 °C. -1 Cooling from 150 ℃ to room temperature at a rate of 3-5 ℃ / h -1 .

7. The preparation method according to claim 2, characterized in that, Step S3 also includes the following steps: after cooling to room temperature, separating the reaction solution by centrifugation, washing and drying the sample.

8. The application of a main group element ion-doped zero-dimensional metal halide luminescent material as described in claim 1 in the field of liquid helium and liquid nitrogen cryogenic detection.

9. The application according to claim 8, characterized in that, Temperature detection in extreme temperature ranges is achieved by utilizing the changes in fluorescence lifetime and fluorescence intensity ratio of luminescent centers of main group element ions at extremely low temperatures.

10. The application according to claim 8, characterized in that, The temperature range for low-temperature testing is 4 K-70 K.

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