Rare earth doped perovskite quantum dot glass and preparation method thereof

Abstract

The invention relates to rare earth doped perovskite quantum dot glass and a preparation method thereof, and belongs to the technical field of inorganic functional materials and optical functional glass. The method comprises the following steps: preparing nanopore SiO2-Al2O3 glass as a matrix by adopting a sol-gel method, adding a lead source and a rare earth europium source, drying and sintering to obtain uniformly-doped porous glass, soaking the uniformly-doped porous glass in a CsBr methanol solution, and generating the CsPbBr3 perovskite quantum dots in situ. In the glass, the CsPbBr3 quantum dots show wavelength-adjustable broadband luminescence, the Eu < 3 + > ions show narrow-band luminescence, and the CsPbBr3 quantum dots and the Eu < 3 + > ions show double-peak reverse fluorescence response under the action of hydrogen chloride gas. The aperture structure can be controlled by adjusting the use amount of the aluminum lactate, so that the size and the luminescence property of the quantum dot and energy transfer between the quantum dot and Eu < 3 + > ions are adjusted, and the luminescence property and the response characteristic are optimized. The material is uniform in doping, stable in structure and suitable for the fields of multiband luminescent devices and gas sensing.

Description

Technical Field

[0001] The present invention relates to the technical fields of functional glass materials and gas sensing technology, and particularly relates to a rare earth doped perovskite quantum dot composite glass material and a preparation method thereof, especially a hydrogen chloride gas sensing glass capable of realizing dual-peak fluorescence response and a construction method thereof, belonging to the cross-research field of the preparation and application of optical gas sensor materials. Background Art

[0002] In recent years, the detection strategy based on dual luminescent substances has attracted wide attention in the field of optical sensing. This strategy usually designs one luminescence peak as a reference signal (reference peak) and the other as a response signal (detection peak), and realizes highly sensitive detection of the target by means of the change in the intensity ratio between the two. Compared with the traditional single-channel detection mode, the dual-peak luminescence system can effectively offset the errors caused by background noise and environmental disturbances, thereby significantly improving the sensitivity, repeatability and dynamic range of detection, and is particularly suitable for fields such as environmental gas monitoring, chemical sensing and fluorescence imaging.

[0003] Due to its high quantum efficiency, adjustable band gap and simple synthesis, perovskite materials show great potential in optical sensing, especially suitable for the anion exchange type response mechanism. Its emission spectrum is generally wide, and the intensity is easily interfered by environmental factors, while rare earth ions (such as Eu 3+ ) have narrow emission lines and stable positions, and have good optical stability and anti-interference ability. Therefore, constructing a "perovskite + rare earth" composite luminescence system can realize a complementary luminescence mechanism: the perovskite peak serves as a detection signal to strongly respond to the target gas, and the rare earth peak serves as a reference signal to provide a steady-state luminescence benchmark, forming a dual-peak luminescence sensor device with a built-in calibration function.

[0004] In the prior art, CN118344003A discloses a method for preparing rare earth doped perovskite quantum dot glass by the high-temperature melting method. Although the coexistence of perovskite and rare earth is realized, this process has obvious limitations. The melting method requires a high temperature (generally exceeding 1000°C), consumes a large amount of energy, and excessive doping easily causes phase separation, resulting in a decrease in the transparency of the material. In addition, the molten glass has a dense structure, lacks a mesoporous structure, and does not have good gas adsorption capacity, which limits its practical application in chemical sensing and other directions; at the same time, the size and distribution of perovskite quantum dots are also difficult to accurately control during the melting process, thus affecting the luminescence performance and sensing stability.

[0005] In contrast, CN117849011A discloses a perovskite mesoporous glass hydrogen chloride sensor prepared by a two-step solution immersion method. Although the anion exchange response mechanism in the perovskite glass is realized, this method requires separate immersion treatments of lead source and cesium salt, and the process flow is complex. Moreover, the introduction of rare earth elements is not involved, and the dual-peak luminescence function cannot be achieved. At the same time, this technology does not provide a means to regulate the pore structure of the glass, making it difficult to control the size and distribution of perovskite quantum dots, thereby limiting the fine adjustment of luminescence intensity and response sensitivity. Summary of the Invention

[0006] In view of the above problems, the present invention proposes a rare earth-doped perovskite quantum dot glass prepared based on the sol-gel method. The porous SiO2-Al2O3 glass matrix adopted has a high specific surface area and good adsorption performance, and can effectively carry and confine the growth of perovskite quantum dots. By precisely regulating the content of aluminum lactate in the precursor, the present invention can effectively adjust the pore size of the glass, and then precisely control the size and distribution of quantum dots, optimizing their optical properties and structural stability.

[0007] Compared with the perovskite glass prepared by the traditional melting method, the present invention uses the sol-gel method to construct a nano-porous SiO2-Al2O3 glass matrix, uniformly immobilizes Eu 3+ ions in the silicate glass network, and controls the generation of the nano-porous structure and the in-situ synthesis of CsPbBr quantum dots. The size and distribution of perovskite quantum dots are effectively controlled through the space confinement effect, overcoming problems such as disordered precipitation of quantum dots and poor particle size dispersity in the melting method, and significantly improving the luminescence uniformity and structural stability. In particular, by regulating the addition ratio of aluminum lactate in the precursor, the present invention realizes the precise adjustment of the pore size of the glass, thereby further regulating the size and luminescence behavior of perovskite quantum dots.

[0008] Further different from the existing preparation method of separately introducing lead source and cesium source through two-step immersion, the present invention introduces the lead source in the sol stage to achieve uniform doping of Pb 2+ in the glass. Subsequently, only by immersing the nano-pores in the CsBr methanol solution, the in-situ generation of CsPbBr3 perovskite quantum dots can be achieved in one step, greatly simplifying the process flow and improving the efficiency of material preparation.

[0009] In addition, Eu 3+ ions are co-doped in the glass. Its emission peak can be used as an internal reference signal, and its intensity does not change with environmental parameters. The luminescence peak of CsPbBr quantum dots is used as the main signal, and its intensity dynamically responds to environmental parameters. The emission peak of Eu 3+ ions and the perovskite luminescence peak jointly construct a dual-channel luminescence response mechanism. When contacting with HCl gas, Cl - in the HCl gas and Br in the CsPbBr3 crystal- Gradual substitution reactions occur, leading to an increase in local defects in the perovskite structure and an enhancement of non-radiative recombination pathways, resulting in a decrease in the green emission intensity. Meanwhile, structural perturbations or redistribution of the excited state may promote energy transfer to Eu 3+ ions, thus enhancing its narrow-band red emission. Therefore, the two luminescent substances exhibit a complementary luminescence characteristic, enabling rapid, high-contrast, and visual detection of hydrogen chloride gas.

[0010] The specific technical solution of the present invention proposes a preparation method of a rare-earth-doped perovskite quantum dot glass, comprising the following steps:

[0011] S1: Dissolve aluminum lactate in deionized water, stir until completely dissolved, add anhydrous ethanol, and finally add a silicon precursor. Continuously stir for 6 - 10 h to form a homogeneous sol. Based on 100 mol% of the silicon precursor, the molar percentages of aluminum lactate, deionized water, and anhydrous ethanol are 2 - 10%, 800 - 1600%, and 700 - 1500% of the silicon precursor, respectively;

[0012] S2: Sequentially add a lead precursor and an europium precursor to the homogeneous sol obtained in step S1, continuously stir for 3 - 5 h to fully dissolve them to form a homogeneous melt sol. The molar percentages of the lead precursor and the europium precursor are 0.05% - 0.25% and 6 - 10% of the silicon precursor, respectively;

[0013] S3: Place the homogeneous sol obtained in step S2 in a polypropylene mold and age at room temperature for 8 - 12 h to obtain a wet gel;

[0014] S4: Subject the wet gel obtained in step S3 to staged drying and stepwise sintering to obtain Pb 2+ and Eu 3+ -doped nanoporous glass;

[0015] S5: Immerse the nanoporous glass obtained in step S4 in a cesium bromide methanol solution, and then perform vacuum drying to prepare the rare-earth-doped perovskite quantum dot glass.

[0016] Further, in step S1, the silicon precursor is selected from any one of tetraethyl orthosilicate and tetramethyl orthosilicate.

[0017] Further, in step S, the lead precursor is selected from any one of lead acetate and lead nitrate.

[0018] In the preparation method of the rare-earth doped perovskite quantum dot glass provided by the present invention, the drying and sintering processes have a crucial impact on the pore structure and luminescence properties of the material. To ensure the complete formation of the glass skeleton and facilitate the subsequent confined growth of quantum dots, the drying process is controlled by a staged heating method, and the sintering process is controlled by a stepped heating method.

[0019] Furthermore, in step S4, the staged drying is specifically as follows:

[0020] (a) Heat from room temperature to 40 - 50 °C at a heating rate of 0.5 - 5 °C / min and hold for 12 - 24 hours;

[0021] (b) Adopt the stepped heating method, with a heating rate of 0.5 - 5 °C / min. After each 10 °C increase, hold for 10 - 16 hours until the temperature reaches 100 - 120 °C;

[0022] (c) Naturally cool to room temperature to obtain a dried body.

[0023] Furthermore, in step S4, the stepped sintering is specifically as follows: Heat from room temperature to 150 - 200 °C at a heating rate of 1 - 5 °C / min and hold for 2 - 4 h; then heat to 300 - 400 °C at a heating rate of 0.5 - 1.5 °C / min and hold for 4 - 8 h; continue to heat to 500 - 600 °C at a rate of 0.1 - 1 °C / min and hold for 4 - 8 h; finally, heat to 700 - 750 °C at a rate of 0.1 - 1 °C / min and hold for 4 - 8 h, and then naturally cool to obtain the Pb 2+ and Eu 3+ doped nanoporous glass.

[0024] Furthermore, in step S4, the average pore diameter of the obtained nanoporous glass is 1.22 - 3.54 nm, and the porosity is 33 - 43%.

[0025] Furthermore, in step S5, the concentration of the cesium bromide methanol solution is 0.1 - 2 mol / L, the soaking time is 1 - 2 hours, and the size of the CsPbBr3 quantum dots in the nanoporous glass after soaking is 2 - 6 nm, and the emission peak is between 480 nm and 510 nm.

[0026] Furthermore, in step S5, the vacuum drying conditions are an absolute pressure ≤ 0.01 bar, a temperature of 60 - 80 °C, and a drying time of 1 - 2 h.

[0027] The present invention also provides a rare-earth doped perovskite quantum dot glass, and the perovskite quantum dot glass is prepared by the above preparation method. The glass contains Eu uniformly dispersed in the silicate network 3+ions and CsPbBr3 quantum dots embedded in nanopores, wherein the ratio of nanopore diameter to quantum dot size is 1:1.64-1.70. 3+ The emission peak of the ion and the luminescence peak of the CsPbBr3 quantum dots form a dual-channel luminescence response system. The luminescence peak of the CsPbBr3 perovskite quantum dots is used as the main signal channel to detect the target anion exchange reaction. 3+ The emission peak of the ion serves as an internal reference signal channel, which responds in coordination with the main signal channel, and realizes visual monitoring of environmental changes through the change of the double peak intensity ratio.

[0028] Beneficial technical effects of the present invention:

[0029] The present invention provides a method for preparing rare-earth-doped perovskite quantum dot glass. Compared with the existing technology, the advantage of this method is that the present invention uses a sol-gel method to efficiently construct rare-earth-doped nanoporous quantum dot glass. In the sol stage, rare earth and quantum dot precursors are incorporated into a matrix, and after sintering, glass with stable rare-earth luminescence is obtained. Subsequently, a material with a porous structure and dual luminescence centers is further prepared by a solution method. During the quantum dot synthesis process, the position of its photoluminescence (PL) emission peak can be effectively changed by adjusting the pore size, and by matching the energy level of the rare earth ions, precise regulation of energy transfer can be achieved, laying a theoretical foundation for dual-peak response detection.

[0030] In actual fluorescence detection applications, the pore structure and dual-luminescence center characteristics of rare-earth-doped nanoporous quantum dot glass are fully utilized. The pores effectively enrich the hydrogen chloride molecules to be measured, prompting them to undergo a halogen anion exchange reaction with the quantum dots, resulting in changes in the position and intensity of the PL emission peak. Compared with traditional single-quantum dot sensors, the present invention provides an additional reference signal by introducing a stable rare-earth luminescence peak. As the intensity of the quantum dot PL emission peak decreases, energy enhances the luminescence of the rare-earth ions through energy transfer pathways, causing the color of the sensing material to gradually change from green to white, and finally to a weak red. This significant color change can be observed by the naked eye.

[0031] Compared with traditional single-luminescence center sensing materials, the dual-luminescence center fluorescent sensing material of the present invention enhances the significance of color change while introducing a reference peak; and the design of the nanopore structure effectively enriches the molecules to be tested, further improving the sensitivity and responsiveness of the probe. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 For Pb in Examples 1, 6, and 7 2+ and Eu 3+ Actual photo of doped nanoporous glass under 395nm ultraviolet light excitation;

[0033] Figure 2 (a) is the photoluminescence (PL) spectra of the rare-earth doped perovskite quantum dot glasses in Examples 1, 2, and 3, and (b) is the physical photo of the rare-earth doped perovskite quantum dot glasses in Examples 1, 2, and 3 under the excitation of 395 nm ultraviolet light;

[0034] Figure 3 (a) and (b) are the transmission electron microscope photo and the scanning transmission electron microscope photo collected in the high-angle annular dark-field (HAADF) mode of the rare-earth doped perovskite quantum dot glass in Example 1, respectively, and (c), (d), (e), and (f) are the energy spectrum distribution maps of Pb, Cs, Br, and Eu elements, respectively;

[0035] Figure 4 (a), (b), and (c) are the pore size distribution maps of the Pb 2+ and Eu 3+ doped nanoporous glasses in Examples 1, 4, and 5, respectively. The inset is the schematic diagram of the glasses with different pore sizes;

[0036] Figure 5 are the photoluminescence (PL) spectra and the excitation spectrum of Eu 3+ of the rare-earth doped perovskite quantum dot glasses in Examples 1, 4, and 5;

[0037] Figure 6 is the time-resolved photoluminescence spectrum during the sensing process of the rare-earth doped perovskite quantum dot glass in Example 1;

[0038] Figure 7 is the CIE1931 chromaticity coordinate diagram during the sensing process of the rare-earth doped perovskite quantum dot glass in Example 1. Detailed implementation manners

[0039] The present invention will be further described below in conjunction with the examples.

[0040] Example 1: Preparation of 2 mol% Al / 8 mol% Eu 3+ / 0.15 mol% Pb 2+ rare-earth doped perovskite quantum dot glass

[0041] Weigh 0.16 g of aluminum lactate and dissolve it in 6 mL of deionized water. Then add 12 mL of absolute ethanol, followed by 6 mL of tetraethyl orthosilicate, and stir at room temperature for 8 h. Then, add 0.013 g of lead acetate and 0.96 g of europium(III) nitrate hexahydrate and continue stirring for 4 h to achieve uniform mixing. Transfer the resulting mixture to a polypropylene mold and age for 10 h. After aging, transfer it to an oven and heat it at a heating rate of 2 °C / min to 50 °C, hold for 16 h, and then use the stepwise heating method and heat it at a heating rate of 2 °C / min, hold for 12 h for every 10 °C increase until reaching 110 °C to form a xerogel, and then take it out and cool it naturally to room temperature. Heat the xerogel in a muffle furnace from room temperature to 175 °C at a heating rate of 3 °C / min and hold for 3 h; then heat it to 350 °C at a heating rate of 1 °C / min and hold for 6 h; continue to heat it to 550 °C at a heating rate of 0.5 °C / min and hold for 6 h; finally heat it to 725 °C at a rate of 0.5 °C / min and hold for 6 h, and then naturally cool it to room temperature to obtain Pb 2+ and Eu 3+ -doped nanoporous glass.

[0042] Immerse the nanoporous glass in a 1 mol / L CsBr methanol solution for 1 h to complete the growth of perovskite quantum dots, and then perform vacuum drying at 70 °C for 1.5 h to remove residual methanol. The rare-earth-doped perovskite quantum dot glass is prepared through this process.

[0043] Example 2: Preparation of 2 mol% Al / 8 mol% Eu 3+ / 0.05 mol% Pb 2+ -doped perovskite quantum dot glass

[0044] Weigh 0.16 g of aluminum lactate and dissolve it in 3.87 mL of deionized water. Then add 10.95 mL of absolute ethanol, followed by 4.00 mL of tetramethyl orthosilicate, and stir at room temperature for 6 h. Then, add 0.0044 g of lead nitrate and 0.96 g of europium(III) nitrate hexahydrate and continue stirring for 3 h to achieve uniform mixing. Transfer the resulting mixture to a polypropylene mold and age for 8 h. After aging, transfer it to an oven and heat it at a heating rate of 0.5 °C / min to 40 °C, hold for 12 h, and then use the stepwise heating method and heat it at a heating rate of 0.5 °C / min, hold for 10 h for every 10 °C increase until reaching 100 °C to form a xerogel, and then take it out and cool it naturally to room temperature. Heat the xerogel in a muffle furnace from room temperature to 150 °C at a heating rate of 1 °C / min and hold for 2 h; then heat it to 300 °C at a heating rate of 0.5 °C / min and hold for 4 h; continue to heat it to 500 °C at a heating rate of 0.1 °C / min and hold for 4 h; finally heat it to 700 °C at a rate of 0.1 °C / min and hold for 4 h, and then naturally cool it to room temperature to obtain Pb2+ and Eu 3+ doped nanoporous glass.

[0045] The nanoporous glass was immersed in a 1 mol / L CsBr methanol solution for 1 h to complete the growth of perovskite quantum dots, and then vacuum dried at 60 °C for 2 h to remove residual methanol. The rare earth doped perovskite quantum dot glass was prepared through this process.

[0046] Example 3: The same as Example 1, only the mass of lead acetate was adjusted to 0.22 g (0.25 mol% Pb 2+ ).

[0047] Example 4: Preparation of 5 mol% Al / 8 mol% Eu 3+ / 0.15 mol% Pb 2+ rare earth doped perovskite quantum dot glass

[0048] Weighed 0.39 g of aluminum lactate and dissolved it in 7.74 mL of deionized water. Subsequently, 23.46 mL of absolute ethanol was added, followed by 6.00 mL of tetraethyl orthosilicate, and stirred at room temperature for 10 h; then, 0.013 g of lead acetate and 0.96 g of europium nitrate hexahydrate were added and stirred for another 5 h to achieve uniform mixing; the resulting mixture was transferred to a polypropylene mold and aged for 12 h. After aging, it was transferred to an oven and heated to 50 °C at a heating rate of 5 °C / min and held for 24 h. Then, the stepwise heating method was adopted and the temperature was increased by 5 °C / min and held at each 10 °C increase for 16 h until 120 °C was reached to form a dry gel, and then taken out and naturally cooled to room temperature. The dry gel was heated in a muffle furnace from room temperature to 200 °C at a heating rate of 5 °C / min and held for 4 h; then heated to 400 °C at a heating rate of 1.5 °C / min and held for 8 h; continued to be heated to 600 °C at a heating rate of 1 °C / min and held for 8 h; finally heated to 750 °C at a rate of 1 °C / min and held for 8 h, and then naturally cooled to room temperature to obtain Pb 2+ and Eu 3+ doped nanoporous glass.

[0049] The nanoporous glass was immersed in a 1 mol / L CsBr methanol solution for 1 h to complete the growth of perovskite quantum dots, and then vacuum dried at 80 °C for 1 h to remove residual methanol. The rare earth doped perovskite quantum dot glass was prepared through this process.

[0050] Example 5: The same as Example 1, only the mass of aluminum lactate was adjusted to 0.79 g (10 mol% Al 3+ ).

[0051] Example 6: The same as Example 1, except that the mass of europium nitrate hexahydrate was adjusted to 0.72 g (6 mol% Eu 3+ ).

[0052] Example 7: The same as Example 1, except that the mass of europium nitrate hexahydrate was adjusted to 1.19 g (10 mol% Eu 3+ ).

[0053] Test Example 1: Luminescence effect of glasses with different rare earth doping concentrations

[0054] Test samples: nanoporous glasses prepared in Example 6, 1, and 7

[0055] Test method: Using a Nikon Z30 camera to take pictures, and recording the luminescence effect of glasses with different rare earth doping concentrations under 395 nm ultraviolet light excitation.

[0056] Figure 1 From left to right in the figure shows the luminescence effect of nanoporous glasses with Eu 3+ doping concentrations of 6 mol%, 8 mol%, and 10 mol% respectively under 395 nm ultraviolet light excitation. It can be seen that Eu 3+ is uniformly doped within this concentration range, and the luminescence effect is obvious.

[0057] Test Example 2: Photoluminescence spectrum test

[0058] Test samples: rare earth doped perovskite quantum dot glasses in Example 1, 2, and 3

[0059] Test equipment: transient fluorescence spectrometer (FLS1000, Edinburgh Instruments, UK)

[0060] As Figure 2 -(a) shows, as the Pb 2+ content decreases from 0.25 mol% to 0.05 mol%, the luminescence peak intensity of the perovskite quantum dot at about 500 nm gradually weakens. The luminescence intensity changes from higher than the 3+ luminescence peak of Eu 5 ions at 612 nm for the 7 D0→ 7 F2 transition to lower than this luminescence peak. The relative intensity of the two luminescent substances can be adjusted within this range, demonstrating excellent dual-channel response regulation ability. Figure 2 -(b) The physical photo further shows the color change caused by the change in the relative intensity of the two luminescent substances.

[0061] Test Example 3: Transmission electron microscope photos and energy spectrum element distribution characterization

[0062] Test samples: rare earth doped perovskite quantum dot glasses prepared in Example 1

[0063] Testing equipment: Transmission electron microscope (Talos F200X, Thermo Fisher, USA)

[0064] As Figure 3 shown in 3-(a) and 3-(b), both the transmission electron microscope photo and the scanning transmission electron microscope photo show that perovskite quantum dots are evenly distributed in the glass. Figure 3 3-(c) shows that Pb elements are mainly enriched in the perovskite quantum dots. Figure 3 3-(d) and Figure 3 3-(e) show that Cs and Br elements are evenly distributed, indicating that there is a certain amount of Cs and Br residue after the soaking treatment. Figure 3 3-(f) shows that Eu elements are evenly dispersed in the glass matrix.

[0065] Test Example 4: Pore size analysis

[0066] Test samples: nanoporous glasses prepared in Examples 1, 4, and 5

[0067] Testing equipment: Physical adsorption instrument (Quantachrome, Anton Paar, Austria)

[0068] Aluminum lactate releases lactic acid during hydrolysis and acts as a pore-forming agent. The mesopore size of the glass can be regulated by controlling the addition amount of aluminum lactate. As Figure 4 shown in 3-(a) to Figure 4 3-(c), as the addition amount of aluminum lactate increases from 2 mol% to 10 mol%, the average pore size of the glass increases from 1.22 nm to 3.54 nm. The change in pore size will directly affect the size of subsequent perovskite quantum dots.

[0069] Test Example 5: Photoluminescence spectrum test

[0070] Test samples: rare earth-doped perovskite quantum dot glasses prepared in Examples 1, 4, and 5

[0071] Testing equipment: Transient fluorescence spectrometer (FLS1000, Edinburgh Instruments, UK)

[0072] As Figure 5 shown, as the doping amount of aluminum lactate increases, the pore size of the glass increases, the size of the perovskite quantum dots increases accordingly, and the emission peak of the perovskite quantum dots gradually redshifts between 483 nm and 507 nm.

[0073] The change in pore size not only affects the size of quantum dots but also optimizes energy transfer by adjusting the spectral overlap between quantum dots and rare-earth ions. Whether the pore size increases or decreases, the energy transfer efficiency can be enhanced by regulating the overlap degree between the size of quantum dots and the spectrum of rare-earth ions. A larger pore size helps increase the size of quantum dots, thereby enhancing spectral overlap and improving the efficiency of energy transfer to Eu 3+ . For smaller pore sizes, effective spectral overlap and energy transfer can still be achieved within a certain range by restricting the size of quantum dots. Therefore, the regulation of pore size and quantum dot size effectively enhances the luminescence characteristics of the dual-luminescence response, especially improving the sensitivity and contrast of the material in gas-sensing applications.

[0074] Test Example 6: Time-Resolved Photoluminescence Spectroscopy Test

[0075] Test Sample: Rare-Earth-Doped Perovskite Quantum Dot Glass Prepared in Example 1

[0076] Test Equipment: Transient Fluorescence Spectrometer (FLS1000, Edinburgh Instruments, UK)

[0077] The sample was placed in a gas-phase sensing sample chamber, and HCl gas with a concentration of 50 ppm was introduced. The change in its photoluminescence (PL) spectrum with reaction time was monitored in real time. As Figure 6 shown, the horizontal axis is the emission wavelength (nm), the vertical axis is the reaction time (min), and the color map represents the luminescence intensity distribution at different wavelengths.

[0078] At the initial stage of exposure, the material exhibited typical green emission of CsPbBr3 perovskite quantum dots at approximately 500 nm, while the luminescence of Eu 3+ ions at 612 nm was weak. As the reaction time progressed, the luminescence of perovskite quantum dots gradually weakened and was accompanied by a slight blue shift. The luminescence of Eu 3+ ions gradually increased, forming an obvious double-peak reverse response trend.

[0079] This change is due to the fact that Cl - in the HCl atmosphere can penetrate along the mesoporous structure of the glass and gradually replace Br - in the perovskite crystal structure, inducing the transformation of CsPbBr 3 to CsPbBr 3-x Cl x , regulating its bandgap structure and causing a blue shift in luminescence. The luminescence peak shifts to the left, as shown by the black arrow on the left in the figure. At the same time, the continuous introduction of Cl - will exacerbate lattice distortion and defect generation, leading to an enhanced non-radiative recombination process and ultimately suppressing the luminescence efficiency of perovskite.

[0080] In contrast, Eu3+ Due to their stable narrow-band luminescence properties, ions, as Figure 6 shown by the black arrow on the right in [reference], have a peak position that does not shift significantly during the sensing process. However, the luminescence intensity increases as the perovskite decays, possibly due to the combined effect of two factors: First, there is partial overlap between the emission region of the blue-shifted perovskite and the excitation region of Eu 3+ , and the excitation energy can be effectively transferred to Eu 3+ ; Second, in the defect-induced non-radiative channel, the excited-state energy is more likely to be transferred to Eu 3+ ions, thereby enhancing their luminescence response.

[0081] Figure 7 Figure [figure number] shows the CIE 1931 chromaticity coordinate diagram of the color change of the material during the gas sensing process. As the PL emission peak of the quantum dots weakens and the luminescence of Eu 3+ increases, the luminescence color of the glass changes from green to white and then to weak red, and this significant color change during the process is clearly visible.

[0082] Through the synergistic effect between the perovskite and rare-earth ions, this material constructs a dual-channel response mechanism: the perovskite peak serves as the response signal, and the Eu 3+ peak serves as a stable reference, which can effectively cancel out environmental disturbances and achieve ratio-type visual sensing triggered by HCl gas. Compared with traditional single luminescent materials, this system has higher contrast, responsiveness, and anti-interference ability, and is suitable for high-reliability gas monitoring applications.

Claims

1. A preparation method of rare earth doped perovskite quantum dot glass, characterized in that, It includes the following steps: S1: Dissolve aluminum lactate in deionized water, stir until completely dissolved, add absolute ethanol, and finally add a silicon precursor. Continuously stir for 6 - 10 h to form a homogeneous sol. Based on 100 mol% of the molar amount of the silicon precursor, the molar percentages of aluminum lactate, deionized water, and absolute ethanol are 2 - 10%, 800 - 1600%, and 700 - 1500% of the silicon precursor, respectively. S2: Sequentially add a lead precursor and an europium precursor to the homogeneous sol obtained in step S1, continuously stir for 3 - 5 h to fully dissolve them to form a homogeneous melt gel. The molar percentages of the lead precursor and the europium precursor are 0.05% - 0.25% and 6 - 10% of the silicon precursor, respectively. S3: Place the homogeneous sol obtained in step S2 in a polypropylene mold and age at room temperature for 8 - 12 h to obtain a wet gel. S4: The wet gel obtained in step S3 is successively subjected to staged drying and stepped sintering to obtain Pb 2+ and Eu 3+ -doped nanoporous glass; S5: Immerse the nanoporous glass obtained in step S4 in a cesium bromide methanol solution, and then perform vacuum drying to prepare a rare earth - doped CsPbBr3 perovskite quantum dot glass.

2. The preparation method of a rare-earth doped perovskite quantum dot glass according to claim 1, characterized in that, In step S1, the silicon precursor is selected from one of tetraethyl orthosilicate and tetramethyl orthosilicate.

3. The preparation method of a rare-earth doped perovskite quantum dot glass according to claim 1, characterized in that, In step S2, the lead precursor is selected from one of lead acetate and lead nitrate.

4. The preparation method of a rare earth doped perovskite quantum dot glass according to claim 1, characterized in that, In step S4, the staged drying specifically is: (a) Raise the temperature from room temperature to 40 - 50 °C at a heating rate of 0.5 - 5 °C / min and keep it warm for 12 - 24 hours; (b) Adopt a step - wise heating method, with a heating rate of 0.5 - 5 °C / min. After each 10 °C increase, keep it warm for 10 - 16 hours until the temperature reaches 100 - 120 °C; (c) Naturally cool to room temperature to obtain a dried body.

5. The preparation method of a rare earth-doped perovskite quantum dot glass according to claim 1, characterized in that, In step S4, the step - wise sintering is carried out in an air atmosphere, specifically: (a) Raise the temperature from room temperature to 150 - 200 °C at a rate of 1 - 5 °C / min and keep it warm for 2 - 4 hours; (b) Raise the temperature to 300 - 400 °C at a rate of 0.5 - 1.5 °C / min and keep it warm for 4 - 8 hours; (c) Raise the temperature to 500 - 600 °C at a rate of 0.1 - 1 °C / min and keep it warm for 4 - 8 hours; (d) Raise the temperature to 700 - 750 °C at a rate of 0.1 - 1 °C / min, keep it warm for 4 - 8 hours, and then naturally cool.

6. The preparation method of a rare earth-doped perovskite quantum dot glass according to claim 1, characterized in that, In step S5, the concentration of the cesium bromide methanol solution is 0.1 - 2 mol / L, the soaking time is 1 - 2 hours, the size of the CsPbBr3 quantum dots in the nanoporous glass after soaking is 2 - 6 nm, and the emission peak is between 480 nm and 510 nm.

7. The preparation method of a rare earth-doped perovskite quantum dot glass according to claim 1, characterized in that, In step S5, the vacuum drying conditions are: absolute pressure ≤ 0.01 bar, temperature is 60 - 80 °C, and the drying time is 1 - 2 h.

8. The preparation method of a rare earth-doped perovskite quantum dot glass according to claim 1, characterized in that, In step S4, the average pore diameter of the obtained nanoporous glass is 1.22 - 3.54 nm, and the porosity is 33 - 43%.

9. The preparation method of a rare earth-doped perovskite quantum dot glass according to claim 1, characterized in that, Eu is uniformly immobilized in the silicate glass network through a sol-gel process 3+ ions, and the generation of nanoporous structures and in-situ synthesis of CsPbBr3 quantum dots are controlled to enable the glass to form a dual-channel luminescence response system, and quantitative monitoring of environmental parameters is achieved through changes in the ratio of the intensities of the two peaks, where: Eu 3+ ion emission peaks serve as internal reference signals, and their intensities do not change with environmental parameters; the luminescence peaks of CsPbBr3 quantum dots serve as main signals, and their intensities respond dynamically to environmental parameters.

10. A rare earth doped perovskite quantum dot glass, characterized in that, The perovskite quantum dot glass is prepared by the preparation method according to any one of claims 1-9, and the glass contains Eu uniformly dispersed in a silicate network 3+ ions and CsPbBr3 quantum dots embedded in nanopores, wherein the ratio of the nanopore diameter to the quantum dot size is 1:1.64 to 1.70, and Eu 3+ The emission peak of the ions and the luminescence peak of the CsPbBr3 quantum dots constitute a dual-channel luminescence response system, and quantitative monitoring of environmental parameters is achieved through changes in the ratio of the two peak intensities.

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