Cadmium-based chloride double-mode luminescent material

Abstract

The application is a cadmium-based chloride double-mode luminescent material. The structural formula of the material is CsCd 1‑x Cl3: xMn 2+ , yEr 3+ , zYb 3+ ; wherein, 0.01<=x<=0.1, 0.01<=y<=0.1, 0.01<=z<=0.2; the material is doped with Mn, Er and Yb ions on the basis of CsCdCl3; and the material can be obtained through a simple hydrothermal method in the preparation. The material obtained by the application solves the problems of traditional double-mode luminescent materials, such as the need for physical blending, the difficulty in performance coordination and poor flexibility compatibility.

Description

Technical Field

[0001] This invention relates to the field of inorganic luminescent materials technology, specifically to a cesium cadmium (CsCdCl3)-based luminescent material, and more specifically, to a CsCdCl3:Mn / Er / Yb triple-doped material with good long afterglow performance and mechanoluminescence response capability, its preparation method, and a flexible luminescent composite thin film material made therefrom. The invention aims to provide a luminescent material with rich luminescence modes, stable performance, and ease of forming into flexible thin films. Background Technology

[0002] Long-persistent light materials can continue to emit light for seconds to hours after excitation stops, finding wide applications in emergency indication, optical information storage, and bioimaging. On the other hand, mechanoluminescent materials can directly convert mechanical stress into light signals, providing a revolutionary solution for real-time, visualized stress sensing, structural health monitoring, and dynamic anti-counterfeiting. Developing materials that combine both long-persistent light and mechanoluminescence properties holds promise for integrating static optical displays with dynamic mechanical responses, expanding their applications in multi-dimensional information encryption and intelligent sensing.

[0003] Cesium cadmium chloride (CsCdCl3) crystals belong to the perovskite structure. Due to their excellent stability, tunable luminescence properties, and ease of ion doping, they have become a hot topic in afterglow material research in recent years. For example, Chen, et al. Full-color, time-valve controllable and Janus-type long-persistent luminescence from all-inorganic halide perovskites. Nat Commun 15, 5281 (2024). This paper reports on the achievement of long afterglow luminescence with tunable color and controllable duration in the visible light region through ion doping using CsCdCl3 as a matrix. However, the research focuses only on the regulation and application of afterglow performance under photoexcitation and does not involve any luminescence performance related to mechanical excitation.

[0004] Therefore, exploring a CsCdCl3-based material system with a simple synthesis process, and simultaneously achieving enhanced long afterglow performance and efficient mechanoluminescence performance through lanthanide ion doping, to compensate for the lack of mechanoluminescence performance in existing cadmium-based materials, has significant scientific research and practical application value. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing materials, such as complex preparation processes, difficulty in achieving multimodal luminescence, and poor reproducibility of mechanoluminescence, by providing a cadmium-based chloride dual-mode luminescent material. This material is based on CsCdCl3 and doped with Mn, Er, and Yb ions; it can be synthesized using a simple hydrothermal method. The material obtained by this invention solves the problems of traditional dual-mode luminescent materials, such as the need for physical blending, difficulty in achieving synergistic performance, and poor flexibility and compatibility.

[0006] The technical solution of this invention is as follows: A cadmium-based chloride dual-mode luminescent material, the structural formula of which is CsCd 1-x Cl3:xMn 2+ ,yEr 3+ ,zYb 3+ ; Where 0.01≤x≤0.1, 0.01≤y≤0.1, 0.01≤z≤0.2, the numbers represent the number of moles of the dopant element.

[0007] Preferably, the material is CsCd. 0.99 Cl3:0.01Mn 2+ 0.05Er 3+ 0.1Yb 3+ .

[0008] When irradiated with 280 nm light, the material produces a red afterglow emission with the main peak at 590 nm, and the specific emission peak coverage reaches the range of approximately 400-750 nm.

[0009] The method for preparing the cadmium-based chloride dual-mode luminescent material includes the following steps: (1) Weigh out the cesium source, cadmium source, manganese source and lanthanide source according to the stoichiometric ratio of the general chemical formula; The cesium source is CsCl; the cadmium source is CdCl2; the manganese source is MnCl2; and the lanthanide source is ErCl3 and YbCl3. (2) Place the weighed cesium source, cadmium source, manganese source / lanthanide element source and hydrochloric acid into a reaction vessel lined with polytetrafluoroethylene and seal it. For every 2-10 mL of hydrochloric acid, add 1 mmol of cesium source, (1-x) mmol of cadmium source, x mmol of manganese source, y mmol of ErCl3 and z mmol of YbCl3. The concentration of the hydrochloric acid is 6~14 mol / L; (3) Heat the reactor to 170~190℃ and keep it at that temperature for 10~15 hours, then cool it down to room temperature within 1500~2500 minutes; The heating rate is 4.5~5.5℃ / min; (4) The reaction product was filtered, washed, and then dried in a ventilated place to obtain cadmium-based chloride dual-mode luminescent material; The cadmium-based chloride dual-mode luminescent material is used as a luminescent agent in flexible luminescent films; The method for preparing the flexible light-emitting thin film includes the following steps: The cadmium-based chloride dual-mode luminescent material, PDMS, and curing agent are magnetically stirred, then ultrasonicated, and then poured into a mold and cured at 70℃~100℃ for 40~70 minutes to obtain the flexible luminescent material. The mass ratio of cadmium-based chloride dual-mode luminescent material, PDMS, and curing agent is 1:0.9~1.1:0.05~0.20. The curing agent is specifically hydrogen-containing silicone oil.

[0010] The essential features of this invention are: This invention utilizes Yb 3+ and Er 3+ Predisposition to replace Cd in the crystal lattice 2+ This inequivalent substitution results in an excess of positive charge. To maintain the overall electroneutrality of the crystal, the lattice spontaneously generates compensating defects with negative charges. In halide perovskites, the most common compensation mechanism is the generation of cation vacancies or interstitial halide ions. 3+ / Er 3+ The heterovalent doping of Yb induces a large number of uniformly distributed cation vacancy defects at suitable depths. These defects act as efficient electron trapping centers, significantly enhancing the material's ability to store electrons. More importantly, Yb 3+ Doping tends to introduce abundant shallow trap levels, leading to an increase in afterglow brightness. 3+ With abundant 4f energy levels, multiple metastable energy levels of varying depths can be formed. These energy levels themselves can act as hierarchical traps, enabling multi-level temporary storage and slow release of energy, further extending the afterglow time. Therefore, the combination of these two factors results in increased afterglow brightness and prolonged afterglow decay time. Simultaneously, larger crystal sizes, higher crystallinity, and fewer surface defects effectively suppress nonradiative recombination, leading to higher afterglow brightness and longer duration. Therefore, controlling the cooling rate during crystal synthesis allows the crystals to grow into larger particles.

[0011] The beneficial effects of this invention include at least the following: 1. Achieved efficient dual-mode luminescence in a single material system: through Mn 2+ With Er 3+ / Yb 3+Co-doping with [a specific agent] was reported to produce mechanoluminescence properties in a CsCdCl3 matrix and significantly enhance its long afterglow performance. The afterglow time can reach 10 hours after UV excitation is stopped; the film material can produce visible red light when subjected to mechanical stimulation such as friction, pressing or stretching.

[0012] 2. Tunable and rich luminescent properties: through Er 3+ / Yb 3+ The introduction of this technology allows for additional upconversion luminescence, enabling the integration of multicolor luminescence and multimode response, which greatly expands its application potential in multidimensional anti-counterfeiting and multi-sensing. 3. After being ground into powder, the crystals can be uniformly dispersed in flexible polymers such as PDMS to form a flexible composite film. This film maintains stable mechanoluminescence and afterglow properties after 50 cycles of friction. Encapsulation within a polymer matrix significantly enhances the material's luminescence stability. Attached Figure Description

[0013] Figure 1 The XRD patterns of the samples obtained in Examples 1, 2, and 3 are shown below. Figure 2 The emission spectra of the samples obtained in Examples 1, 2, and 3 are shown. Figure 3 The afterglow spectra of the samples obtained in Examples 1, 2, and 3 are shown. Figure 4 The XRD patterns of the samples obtained in Examples 4, 5, and 6 are shown. Figure 5 The emission spectra of the samples obtained in Examples 4, 5, and 6 are shown. Figure 6 The afterglow spectra of the samples obtained in Examples 4, 5, and 6 are shown. Figure 7 The XRD pattern of CsCdCl3:Mn / Er / Yb obtained in Example 7; Figure 8 The excitation and emission spectra of CsCdCl3:Mn / Er / Yb obtained in Example 7 are shown. Figure 9 The upconversion spectrum of CsCdCl3:Mn / Er / Yb obtained in Example 7 under 980 nm wavelength excitation; Figure 10 The images show the afterglow decay spectra of different ions doped with CsCdCl3 as the matrix obtained in Examples 2, 5, and 7. Figure 11 The afterglow decay spectrum of CsCdCl3:Mn / Er / Yb obtained in Example 7 over 10 hours; Figure 12 The photoluminescence afterglow and mechanoluminescence spectra of CsCdCl3:Mn / Er / Yb obtained in Example 8 are shown. Figure 13 The images show the force-induced spectra of the flexible thin film obtained in Example 8 under different forces. Figure 14 The images show the mechanoluminescence spectra of the flexible thin film obtained in Example 8 at different temperatures. Figure 15 The image shows the mechanoluminescence stability spectrum of the flexible thin film obtained in Example 8 at room temperature. Figure 16 The image shows the force-induced emission spectrum of the flexible film obtained in Example 8 after the afterglow decays to a certain intensity at room temperature. Detailed Implementation

[0014] Example 1: Preparation method of the present invention: Weigh 1 mmol CsCl and 1 mmol CdCl2, add the weighed sample to 20 mL of polytetrafluoroethylene, then add 4 mL of 12 mol / L hydrochloric acid solution, then put the polytetrafluoroethylene into a reaction vessel, tighten the reaction vessel and put it into an oven, set the oven reaction program to raise the temperature from 25°C to 180°C within 30 minutes, maintain it at 180°C for 12 hours, then set the program to cool down, and lower the temperature from 180°C to 25°C over 2000 minutes. After the reaction program is completed, take out the reaction vessel, first pour out the hydrochloric acid in the polytetrafluoroethylene liner, then pour the crystals at the bottom onto filter paper, then wash the crystals with ethanol solution, wash three times, then replace the crystals on a brand new filter paper, put it into an oven at 60°C and dry for 2 hours, grind the dried crystals into powder to obtain CsCdCl3, and mark it.

[0015] Example 2: The other steps are the same as in Example 1, except that the preparation of materials is changed from "weighing 1 mmol CsCl, 1 mmol CdCl2" to "weighing 1 mmol CsCl, 0.99 mmol CdCl2, 0.01 mmol MnCl2". This yields CsCd 0.99 Cl3:1% Mn.

[0016] Example 3: The other steps are the same as in Example 1, except that the preparation of materials is changed from "weighing 1 mmol CsCl, 1 mmol CdCl2" to "weighing 1 mmol CsCl, 0.95 mmol CdCl2, 0.05 mmol MnCl2". This yields CsCd 0.95 Cl3:5% Mn.

[0017] Test conditions: The crystal structure of the sample was determined using a Rigaku X-ray diffractometer with a Cu target as the radiation source, a tube voltage of 40 kV, a tube current of 40 mA, and a scan step size of 0.02. o The scanning speed is 15 o ·min -1 The scanning range is 10. o -60 o The emission spectrum, excitation spectrum, afterglow emission spectrum, and afterglow decay spectrum of the samples were obtained using an FS-5 spectrometer, while the mechanoluminescence spectrum was obtained using a fiber optic spectrometer from Ruhai Optics.

[0018] Experimental results: Figure 1 The given are (1) CsCdCl3, (2) CsCd 0.99 Cl3:1% Mn, (3)CsCd 0.95 The XRD spectra of the three samples (Cl3:5% Mn) show that the diffraction peaks of the product match the standard peaks very well, indicating that the crystalline phase product with the corresponding crystal structure has been synthesized.

[0019] Figure 2 The given are (1) CsCdCl3, (2) CsCd 0.99 Cl3:1% Mn, (3)CsCd 0.95 The emission patterns of three samples (Cl3:5% Mn) show that all three samples emit red light, with the emission peak centered at 610 nm.

[0020] Figure 3 shows the afterglow decay diagrams for the three samples.

[0021] Test conditions: After irradiation with a 254 nm low-pressure mercury lamp for 3 min to excite and charge, the light decayed for 10 s before being placed in the FS-5 spectrometer to test the afterglow decay at 590 nm.

[0022] Experimental results: As can be seen from the figure, CsCd 0.99 The Cl3:1% Mn sample exhibited the best afterglow brightness.

[0023] Example 4: The preparation method of this invention is as follows: Weigh 1 mmol CsCl, 0.99 mmol CdCl2, 0.01 mmol MnCl2, and 0.01 mmol ErCl3. Add the weighed sample to 20 mL of polytetrafluoroethylene (PTFE), then add 4 mL (12 mol / L) hydrochloric acid. Place the PTFE mixture into a reaction vessel, tighten the vessel, and place it in an oven. Set the oven reaction program to increase the temperature from 25°C to 180°C over 30 minutes, maintain the temperature at 180°C for 12 hours, and then decrease the temperature from 180°C to 25°C over 2000 minutes. After the reaction program is complete, remove the reaction vessel, first pour out the hydrochloric acid from the PTFE liner, then pour the crystals from the bottom onto filter paper. Wash the crystals with ethanol solution three times, then transfer the crystals to fresh filter paper and bake in an oven at 60°C for 2 hours. Grind the dried crystals into powder to obtain CsCd. 0.99 Cl3: 1% Mn 1% Er, and label it accordingly.

[0024] Example 5: The other steps are the same as in Example 4, except that the preparation of materials is changed from "weighing 1 mmol CsCl, 0.99 mmol CdCl2, 0.01 mmol MnCl2, and 0.01 mmol ErCl3" to "weighing 1 mmol CsCl, 0.99 mmol CdCl2, 0.01 mmol MnCl2, and 0.05 mmol ErCl3". This yields CsCd 0.99 Cl3: 1% Mn 5% Er.

[0025] Example 6: The other steps are the same as in Example 4, except that the preparation of materials is changed from "weighing 1 mmol CsCl, 0.99 mmol CdCl2, 0.01 mmol MnCl2, and 0.01 mmol ErCl3" to "weighing 1 mmol CsCl, 0.99 mmol CdCl2, 0.01 mmol MnCl2, and 0.1 mmol ErCl3". This yields CsCd 0.99 Cl3: 1% Mn 10% Er.

[0026] Test conditions: Same as Example 1 Experimental results: Figure 4 The given value is (1) CsCd 0.99 Cl3: 1% Mn 1% Er, (2) CsCd 0.99 Cl3: 1% Mn 5%Er, (3) CsCd 0.99Cl3: 1% Mn 10% Er. The XRD spectra of the three samples show that the diffraction peaks of the product match the standard peaks very well with those of the standard, indicating that the crystal phase product with the corresponding crystal structure has been synthesized.

[0027] Figure 5 The given value is (1) CsCd 0.99 Cl3: 1% Mn 1% Er, (2) CsCd 0.99 Cl3: 1% Mn 5% Er, (3) CsCd 0.99 Cl3: 1% Mn 10% Er, emission patterns of three samples. The images show that all three samples emit red light, with the emission peak centered at 610 nm.

[0028] Figure 6 shows (1) CsCd 0.99 Cl3: 1% Mn 1% Er, (2) CsCd 0.99 Cl3: 1% Mn 5% Er, (3) CsCd 0.99 Cl3: 1% Mn 10% Er, afterglow decay diagrams of three samples, from which CsCd can be seen. 0.99 The Cl3:1% Mn 5%Er sample exhibited the best afterglow brightness.

[0029] Example 7: The preparation method of this invention is as follows: Weigh 1 mmol CsCl, 0.99 mmol CdCl2, 0.01 mmol MnCl2, 0.05 mmol ErCl3, and 0.1 mmol YbCl3. Add the weighed sample to 20 mL of polytetrafluoroethylene (PTFE), then add 4 mL (12 mol / L) hydrochloric acid. Place the PTFE mixture into a reaction vessel, tighten the vessel, and place it in an oven. Set the oven reaction program to increase the temperature from 25°C to 180°C over 30 minutes, maintain the temperature at 180°C for 12 hours, and then decrease the temperature from 180°C to 25°C over 2000 minutes. After the reaction program is complete, remove the reaction vessel, first pour out the hydrochloric acid from the PTFE liner, then pour the crystals from the bottom onto filter paper, and then wash the crystals with ethanol solution three times. After washing, transfer the crystals to fresh filter paper and place them in an oven at 60°C for 2 hours. Grind the dried crystals into powder to obtain CsCd. 0.99 Cl3:1% Mn 5% Er10%Yb, and label it accordingly.

[0030] Test conditions: The crystal structure of the sample was determined using a Rigaku X-ray diffractometer with a Cu target as the radiation source, a tube voltage of 40 kV, a tube current of 40 mA, and a scan step size of 0.02. o The scanning speed is 15 o·min -1 The scanning range is 10. o -60 o The emission spectrum, excitation spectrum, afterglow emission spectrum, and afterglow decay spectrum of the samples were obtained using an FS-5 spectrometer, while the mechanoluminescence spectrum was obtained using a fiber optic spectrometer from Ruhai Optics.

[0031] Experimental results: Figure 7 The given value is CsCd 0.99 The XRD pattern of the Cl3:1% Mn 5% Er 10%Yb sample shows that the diffraction peaks of the product match the standard peaks very well, indicating that the crystal phase product with the corresponding crystal structure has been synthesized.

[0032] Figure 8 The given value is CsCd 0.99 The excitation and emission diagrams of the Cl3:1% Mn 5% Er 10%Yb sample show that the optimal excitation wavelength of the sample is around 280 nm, and the optimal emission wavelength under ultraviolet excitation is 610 nm.

[0033] Figure 9 The given value is CsCd 0.99 The upconversion luminescence pattern of the Cl3:1% Mn 5% Er 10%Yb sample excited at 980 nm shows that the emission peak originates from the luminescence of Er ions. This indicates that the introduction of Yb ions endows the crystal with upconversion luminescence properties.

[0034] Figure 10 shows the afterglow decay diagram of CsCdCl3 matrix doped with different ions.

[0035] Test conditions: After irradiation with a 254 nm low-pressure mercury lamp for 1 min to excite and charge, the light decayed for 10 s before being placed in the FS-5 spectrometer to test the afterglow decay.

[0036] Experimental results: From Figure 10 It can be seen that CsCd 0.99 The Cl3:1% Mn 5% Er 10%Yb sample exhibited the strongest initial afterglow intensity, and its afterglow decay rate was relatively slower than that of the CsCdC3:Mn sample, indicating that the introduction of Er and Yb ions provided abundant traps, enhancing the material's ability to store electrons.

[0037] Figure 11 The given value is CsCd 0.99 Attenuation of Cl3:1% Mn 5% Er 10%Yb sample over 10 hours.

[0038] Test conditions: After irradiation with a 254 nm low-pressure mercury lamp for 3 min to excite and charge, the sample was placed in the FS-5 spectrometer to test the afterglow decay at 590 nm.

[0039] Example 8: The preparation method of the present invention: CsCd 0.99 The Cl3:1% Mn 5% Er 10% Yb crystals are ground into powder. 1g of powder is weighed and placed in a glass bottle. Then, 1g of PDMS and 0.1g of curing agent (commercial PDMS curing agent, Sylgard 184, Dow Corning) are added to the glass bottle. The mixture is magnetically stirred for 20 minutes and ultrasonicated for 5 minutes. The solution is then poured into a mold and cured at 70°C for 2 hours to obtain the flexible luminescent material.

[0040] Test conditions: The photoluminescence spectrum was obtained using an FS-5 spectrometer with an excitation wavelength of 280 nm and a detection wavelength of 590 nm. After irradiation with a 254 nm low-pressure mercury lamp for 30 s, the material was placed in the FS-5 spectrometer to measure the afterglow decay at 590 nm. Mechanoluminescence spectra can also be obtained by rubbing the thin film material with a fiber optic probe from Ruhai Optics.

[0041] Experimental results: Figure 12 The given value is CsCd 0.99 The photoluminescence, afterglow, and mechanoluminescence spectra of the flexible thin film after mixing Cl3:1% Mn 5% Er 10% Yb powder and PDMS show that the afterglow and mechanoluminescence of the sample both exhibit red emission, with the emission peak centered at 600 nm.

[0042] Figure 13 The given value is CsCd 0.99 Mechanoluminescence spectrum of a flexible thin film composed of Cl3:1% Mn 5% Er 10% Yb powder and PDMS.

[0043] Test conditions: The probe of the fiber optic spectrometer was rubbed with different forces on the thin film.

[0044] Experimental results: The mechanoluminescence intensity of the thin film material increases with the increase of external force.

[0045] Figure 14 The given value is CsCd 0.99 Mechanoluminescence spectra of a flexible thin film composed of Cl3:1% Mn 5% Er 10% Yb powder and PDMS at different temperatures.

[0046] Test conditions: A thin film material was divided into four pieces of the same size and placed on heating stages at 25℃, 50℃, 100℃, and 150℃ respectively. After being placed on the heating stages for half an hour, the films were irradiated with a 254 nm ultraviolet lamp for 10 seconds, and then irradiated for 2 seconds. The probe of the fiber optic spectrometer was then rubbed with the same force on the films at different temperatures. The luminescence intensity of the materials at different temperatures was recorded using the fiber optic spectrometer.

[0047] Experimental results: The luminescence intensity of the flexible thin film material decreases as the temperature increases.

[0048] Figure 15 The given value is CsCd 0.99 Mechanoluminescence spectrum of a flexible thin film composed of Cl3:1% Mn 5% Er 10% Yb powder and PDMS.

[0049] Test conditions: Irradiate the thin film material with a 254 nm UV lamp for 10 s, and after a 2 s decay, rub the probe of the fiber optic spectrometer against the thin film material. The area of ​​the integrated mechanoluminescence spectrum is used to obtain a data point in the figure. The same conditions are used to excite the thin film material before each test. The same test conditions are repeated 50 times to obtain the cycle stability graph of the thin film sample at room temperature.

[0050] Experimental results: The mechanoluminescence properties of the thin film material have good stability.

[0051] Figure 16 The given value is CsCd 0.99 Afterglow decay and mechanoluminescence spectra of a flexible thin film composed of Cl3:1% Mn 5% Er 10% Yb powder and PDMS.

[0052] Test conditions: Irradiate the film material with a 254 nm UV lamp for 1 minute. Record the afterglow intensity of the film material with the probe of a fiber optic spectrometer every 5 seconds. After recording the fourth afterglow intensity, rub the film material with the probe of the fiber optic spectrometer to record the mechanoluminescence intensity of the film material. Record the change in the mechanoluminescence intensity of the sample between the fifth and sixth points of the afterglow intensity compared with the mechanoluminescence intensity between the fourth and fifth points of the afterglow intensity.

[0053] Experimental results: The afterglow intensity of the film gradually decreases over time, and its brightness increases on top of the original afterglow brightness when the sample is rubbed.

[0054] Matters not covered in this invention are common knowledge.

Claims

1. A cadmium-based chloride dual-mode luminescent material, characterized in that, The structural formula of this material is CsCd. 1-x Cl3:xMn 2+ ,yEr 3+ ,zYb 3+ ; Where 0.01≤x≤0.1, 0.01≤y≤0.1, 0.01≤z≤0.

2.

2. The cadmium-based chloride dual-mode luminescent material as described in claim 1, characterized in that, The material is CsCd. 0.99 Cl3:0.01Mn 2+ 0.05Er 3+ 0.1Yb 3+ .

3. The cadmium-based chloride dual-mode luminescent material as described in claim 1, characterized in that, When the material is irradiated with 280 nm light, it produces a red afterglow emission with the main peak at 590 nm, and the emission peak covers the range of 400-750 nm.

4. The preparation method of the cadmium-based chloride dual-mode luminescent material as described in claim 1, characterized in that, The method includes the following steps: (1) Weigh out the cesium source, cadmium source, manganese source and lanthanide source according to the stoichiometric ratio of the general chemical formula; The cesium source is CsCl; the cadmium source is CdCl2; the manganese source is MnCl2; and the lanthanide source is ErCl3 and YbCl3. (2) Place the weighed cesium source, cadmium source, manganese source / lanthanide element source and hydrochloric acid into a reaction vessel lined with polytetrafluoroethylene and seal it. For every 2-10 mL of hydrochloric acid, add 1 mmol of cesium source, (1-x) mmoL of cadmium source, x mmoL of manganese source, y mmoL of ErCl3 and z mmoL of YbCl3; (3) Heat the reactor to 170~190℃ and keep it at that temperature for 10~15 hours, then cool it down to room temperature within 1500~2500 minutes; (4) The reaction product was filtered, washed, and then dried in a ventilated place to obtain cadmium-based chloride dual-mode luminescent material.

5. The preparation method of the cadmium-based chloride dual-mode luminescent material as described in claim 4, characterized in that, In step (2), the concentration of hydrochloric acid is 6~14 mol / L.

6. The preparation method of the cadmium-based chloride dual-mode luminescent material as described in claim 4, characterized in that, In step (4), the heating rate is 4.5~5.5℃ / min.

7. The application of the cadmium-based chloride dual-mode luminescent material as described in claim 1, characterized in that, It is used as a luminescent agent in flexible luminescent films.

8. The application of the cadmium-based chloride dual-mode luminescent material as described in claim 7, characterized in that, The method for preparing the flexible light-emitting thin film includes the following steps: The cadmium-based chloride dual-mode luminescent material, PDMS, and curing agent are magnetically stirred, then ultrasonicated, and then poured into a mold and cured at 70℃~100℃ for 40~70 minutes to obtain the flexible luminescent material. The mass ratio of cadmium-based chloride dual-mode luminescent material, PDMS, and curing agent is 1:0.9~1.1:0.05~0.20.

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