Transition metal and chalcogen doped metal halide and preparation method and application thereof

Abstract

The invention relates to the technical field of luminescent materials, and discloses a preparation method and application of a transition metal and chalcogen ion doped metal halide high-efficiency wide-spectrum luminescent material, the chemical formula of the transition metal and chalcogen ion doped metal halide is Cs2Sn1-x-yCl6: x% Te < 4 + >, yMo < 4 + >, the ultra-wideband fluorescent powder converted light emitting diode (LED) covers the range from visible light (VIS) to near infrared light (NIR), and shows remarkable potential in practical application. According to the invention, ultra-wide spectrum emission from 400 nm to 1400 nm is realized in Mo < 4 + >-Te < 4 + > co-doped Cs2SnCl6, and the photoluminescence quantum yield of 95.3% is achieved, the excellent performance is realized through efficient energy transfer from Te < 4 + > to Mo < 4 + > and passivation synergistic effect of vacancy defects, and the performance can be verified through theoretical calculation and spectral research; finally, the ultra-wideband fluorescent powder conversion LED based on the Mo < 4 + > and Te < 4 + > co-doped Cs2SnCl6 is successfully prepared and is applied to the fields of blood gas analysis and night vision imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of luminescent materials, and in particular to transition metal and oxygen group element doped metal halides and preparation methods and applications thereof. Background Art

[0002] Ultra-broadband light sources emitting in the visible and near-infrared (VIS-NIR) spectral range have important application value in many cutting-edge fields, including telecommunications, biomedical imaging, smart agriculture, chemical sensing, food testing, and VR / AR technology. Currently available visible-near-infrared ultra-broadband light sources mainly rely on technologies such as xenon-halogen tungsten lamps, supercontinuum light sources, and laser diode arrays, but these traditional light sources generally have problems such as short service life, low energy conversion efficiency, large size, and high manufacturing cost. In contrast, phosphor-converted light-emitting diodes (pc-LEDs) are considered by the industry to be the ideal choice for the next generation of solid-state light sources due to their advantages such as excellent service life, high energy conversion efficiency, and compact structural design. In particular, miniaturized VIS-NIR pc-LED devices, with their unique size advantages, can be well integrated into portable smart devices such as smartphones and smart watches, which can not only realize real-time human physiological parameter monitoring, but also provide accurate spectral data support for food freshness assessment, origin traceability, and quality analysis. Among the key components of pc-LED devices, phosphors directly determine the output power and spectral distribution characteristics of the light source. Therefore, the development of ultra-wideband phosphor materials with ultraviolet or blue light excitation capabilities and covering the entire VIS-NIR band has become an important direction in the current research field of optoelectronic materials.

[0003] Previous studies have shown that ultra-broadband phosphors from VIS to NIR can be obtained by incorporating rare earth ions and transition metal ions into the matrix. Rare earth ions with 5d-4f transitions are generally considered to be key candidates for producing broadband emission. In addition, utilizing the strong absorption of 5d-4f to sensitize transition metal ions with dd transitions is also considered to be an important strategy to obtain broadband emission ranging from VIS to NIR. However, their spectral distribution is not sufficient (< 800 nm), which limits general spectral analysis because most molecular radicals have characteristic absorption above 830 nm.

[0004] In recent years, the breakthrough development of metal halide materials with low phonon energy has opened up an innovative path for the design of new phosphors. Among them, constructing an energy transfer channel from self-trapped excitons (STE) to rare earth ions or transition metal ions has become an effective design strategy for achieving VIS-NIR ultra-wideband emission phosphors. However, this strategy still faces many challenges in practical applications: first, the energy level mismatch between ion pairs leads to limited energy transfer efficiency; second, the severe cross-relaxation phenomenon of rare earth ion pairs significantly reduces the luminescence performance of the material. These factors together lead to the common problems of low photoluminescence quantum yield (PLQY) and complex preparation process in such phosphors. Therefore, the development of single-phase ultra-wideband emission materials with high quantum efficiency (PLQY >90%) and covering both visible and near-infrared bands has become a key scientific problem to promote the development of ultra-wideband LED light source technology. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose transition metal and oxygen group element doped metal halide and its preparation method and application.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: Transition metal and oxygen group element doped metal halide, the chemical formula of the transition metal and oxygen group element doped metal halide is Cs 2 Sn 1-x-y Cl 6 :x%Te 4+ ,yMo 4+ , 0<x≤50,0<y≤50.

[0007] Preferably, the Te 4+ The doping content is 1.75%, Mo 4+ The doping content is 6.56%; The transition metal and oxygen group element doped metal halide samples are micrometer-sized; The transition metal and oxygen group element doped metal halide sample has a cubic crystal phase structure.

[0008] The method for preparing the above-mentioned transition metal and oxygen group element doped metal halide comprises the following steps: Step 1: Tellurium dioxide, tin tetrachloride pentahydrate, and molybdenum pentachloride are placed in a container containing 5 ml of hydrochloric acid solution, stirred thoroughly, and cesium carbonate dissolved in 2 ml of hydrochloric acid solution is added to the container to precipitate a reaction product; Step 2: The reaction product obtained in step 1 is purified by centrifugation several times with ethanol, and the purified precipitate is placed in an oven for drying to obtain the transition metal and oxygen group element doped metal halide.

[0009] Preferably, the molar ratio of tellurium dioxide to tin tetrachloride pentahydrate in step 1 is 3:17.

[0010] Preferably, in step 1, the volume ratio of the hydrochloric acid solution contained in the container to the hydrochloric acid solution used to dissolve cesium carbonate is 5:2.

[0011] Preferably, the centrifugal speed for centrifugal purification in step 2 is 5000 rpm / min.

[0012] Preferably, in step 2, the number of centrifugal purifications is 3 times, and the centrifugation time for each time is 5 min.

[0013] Preferably, the oven temperature in step 2 is 80°C.

[0014] Preferably, the drying time in step 2 is 12 h.

[0015] The above-mentioned transition metal and oxygen group element doped metal halide applications in night vision and blood gas analysis.

[0016] The beneficial effects of the present invention are: The present invention proposes a Mo 4+ -Te 4+ Co-doped Cs 2 SnCl 6 Double perovskite phosphors can achieve dual emission characteristics. 4+ and Mo 4+ The phosphor has a synergistic effect, and has high-efficiency luminescence ability in both visible light and near-infrared regions.

[0017] First, Te 4+ The ns² electronic structure of Mo introduces new light absorption channels and provides a visible light emission path. 4+ The presence of Te makes the material have broadband near-infrared emission characteristics. This doping system exhibits excellent spectral response ability in the process of fluorescence emission. 4+ The sp transition of Mo can be effectively excited by 390 nm commercial UV LED chips. 4 + The d-orbital electrons provide energy transfer channels, thereby enhancing the near-infrared emission intensity.

[0018] Next, select Cs 2 SnCl 6 As a matrix material, it can provide good optical and structural stability. Its low phonon energy can provide Mo 4+ The d-orbital electrons provide a weak crystal field environment, promoting ( 1 T 2g / 1 E g) → ( 3 T 1g ) transition, improving the efficiency of near-infrared photoluminescence. At the same time, due to the Te 4+ and Mo 4+ All are tetravalent cations, which can stably replace Sn in the lattice 4 + , effectively avoiding charge imbalance and the introduction of corresponding defects, thereby reducing non-radiative recombination and improving luminescence performance. 2 SnCl 6 The wide bandgap property ensures that the host matrix will not interfere with the excitation and emission process of the dopant, providing a stable doping environment for efficient luminescence.

[0019] The ultra-wideband phosphor-converted light-emitting diode (LED) proposed in the present invention covers the range from visible light (VIS) to near-infrared light (NIR). Its excellent optical performance and stability make it show great potential value in application scenarios such as night vision imaging and blood gas analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The different concentrations of xMo in the embodiments of the invention 4+ -1.75%Te 4+ Doped Matrix Cs 2 SnCl 6 XRD pattern of Figure 2 6.56%Mo in the invention embodiment 4+ -1.75%Te 4+ Doped Matrix Cs 2 SnCl 6 SEM electron microscope image; Figure 3 In the embodiment of the invention, undoped, Te 4+ Single doping, Mo 4+ Single doping, and Te 4+ 、Mo 4+ Co-doped Cs 2 SnCl 6 Absorption spectrum of Figure 4 The different concentrations of xMo in the embodiments of the invention 4+ -1.75%Te 4+ Doped Cs 2 SnCl 6 Visible emission spectrum of Figure 5 The different concentrations of xMo in the embodiments of the invention 4+ -1.75%Te 4+ Cs-doped 2 SnCl 6Near-infrared emission spectrum of Figure 6 6.56%Mo in the invention embodiment 4+ -1.75%Te 4+ Doped Cs 2 SnCl 6 Photoluminescence quantum efficiency; Figure 7 The different concentrations of xMo in the embodiments of the invention 4+ -1.75%Te 4+ Doped Cs 2 SnCl 6 Medium 4+ Fluorescence lifetime at 568 nm emission; Figure 8 6.56%Mo in the invention embodiment 4+ -1.75%Te 4+ Doped Cs 2 SnCl 6 and 1.75%Te 4+ Doped Cs 2 SnCl 6 PIA decay kinetics; Fig. 9 It is a near infrared temperature spectrum diagram (4-300 K) in the embodiment of the invention; Fig.10 is the dependence of half-peak width on temperature; Fig.11 To propose Mo 4+ -Te 4+ Doped Cs 2 SnCl 6 Schematic diagram of the luminescence mechanism; Fig.12 Schematic diagram of the prepared infrared LED for blood oxygen detection and night vision applications. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0022] Example 1: First, 0.2394 mg of tellurium dioxide and 0.298 g of tin tetrachloride pentahydrate were dissolved in 5 ml of hydrochloric acid solution and stirred continuously. Subsequently, a hydrochloric acid solution containing 0.325 g of cesium carbonate was added to the above solution, and a precipitate was immediately generated. Finally, the precipitate was dissolved in ethanol and centrifuged at 5000 rpm / min for 5 min. The above steps were repeated twice, and the obtained precipitate was placed in an oven at 70 ° C and dried for 12 h. The obtained powder was 1.75%Te 4+ Doped Matrix Cs 2 SnCl 6 sample.

[0023] Example 2: 2.73 mg of molybdenum pentachloride, 0.2394 mg of tellurium dioxide, and 0.298 g of tin tetrachloride pentahydrate were placed in 5 ml of hydrochloric acid solution and stirred continuously using a magnetic particle. At the same time, cesium carbonate dissolved in 2 ml of hydrochloric acid solution was added to the above solution, and a precipitate was immediately generated. The other steps were the same as in Example 1.

[0024] Example 3: 13.66 mg of molybdenum pentachloride, 0.2394 mg of tellurium dioxide, and 0.298 g of tin tetrachloride pentahydrate were placed in 5 ml of hydrochloric acid solution and stirred continuously using a magnetic particle. At the same time, cesium carbonate dissolved in 2 ml of hydrochloric acid solution was added to the above solution, and a precipitate was immediately generated. The other steps were the same as those in Example 1.

[0025] Example 4: 27.32 mg of molybdenum pentachloride, 0.2394 mg of tellurium dioxide, and 0.298 g of tin tetrachloride pentahydrate were placed in 5 ml of hydrochloric acid solution and stirred continuously using a magnetic particle. At the same time, cesium carbonate dissolved in 2 ml of hydrochloric acid solution was added to the above solution, and a precipitate was immediately generated. The other steps were the same as in Example 1.

[0026] Example 5: 54.66 mg of molybdenum pentachloride, 0.2394 mg of tellurium dioxide, and 0.298 g of tin tetrachloride pentahydrate were placed in 5 ml of hydrochloric acid solution and stirred continuously using a magnetic particle. At the same time, cesium carbonate dissolved in 2 ml of hydrochloric acid solution was added to the above solution, and a precipitate was immediately generated. The other steps were the same as in Example 1.

[0027] Example 6: 109.29 mg of molybdenum pentachloride, 0.2394 mg of tellurium dioxide, and 0.298 g of tin tetrachloride pentahydrate were placed in 5 ml of hydrochloric acid solution and stirred continuously using a magnetic particle. At the same time, cesium carbonate dissolved in 2 ml of hydrochloric acid solution was added to the above solution, and a precipitate was immediately generated. The other steps were the same as in Example 1.

[0028] Examples 2 to 6 are prepared according to the same synthesis method as above, except that the content of molybdenum pentachloride added is changed, the other steps are completely the same.

[0029] The X-ray diffraction spectra (XRD) of the materials of Example 1 to Example 6 prepared in the present invention are as follows: Figure 1 As shown in the figure, it shows that the phase purity of this type of matrix material is very high. At the same time, with the increase of alkali Mo ion doping concentration, the XRD peak moves to the large angle direction, which is due to the Mo 4+ The ionic radius (0.65 Å) is smaller than that of Sn 4+ The ionic radius (0.69 Å) causes the lattice contraction.

[0030] like Figure 2 Typical sample Example 3 6.56% Mo 4+ -1.75%Te 4+ Doped Matrix Cs 2 SnCl 6 From the scanning electron microscope image, it can be seen that the prepared material is micron-sized. Figure 3 The undoped, Te 4+ Single doping, Mo 4+ Single doping, and Te 4+ 、Mo 4+ Co-doped Cs 2 SnCl 6 Absorption spectrum of undoped Cs 2 SnCl 6 Due to its intrinsic electronic transition, there is no strong absorption above 330 nm. 4+ After doping, the Te 4+1 S 0 - 3 P 1 Additional absorption bands. 4+ In the sample with Mo, the absorption is enhanced in the 270-800 nm spectral range, which is consistent with the 4+ The dd transition (d 2 configuration). Figure 4-5 The different concentrations of xMo in the embodiments of the invention 4+ -1.75%Te 4+ Doped Cs 2 SnCl 6 Visible emission spectrum and near-infrared emission spectrum; in the absence of Mo 4+ Under the condition of ion doping, Te 4+ Doped Cs 2 SnCl 6Exhibiting broadband warm white emission at 568 nm, along with Mo 4+ With the introduction of ions, the luminescence intensity in the visible spectrum region gradually decreases, which is due to the Mo 4+ The near-infrared luminescence intensity of the dd transition of the ions gradually increases and 4+ When the ion doping concentration is 6.56mol%, the intensity of near-infrared luminescence reaches the highest. 4+ Ion doping concentration, Mo 4+ The ion luminescence weakened, which is due to the luminescence quenching caused by the increase in ion concentration. In addition, we also tested 6.56%Mo 4+ -1.75%Te 4+ Doped Cs 2 SnCl 6 The fluorescence quantum efficiency of the sample, such as Figure 6 As shown, the fluorescence quantum efficiency in the visible light region is 59.0%, the fluorescence quantum efficiency in the near-infrared light region is 36.3%, and the total fluorescence quantum efficiency is 95.3%, which is the highest value among the currently reported visible-infrared luminescent materials.

[0031] To verify Mo 4+ -%Te 4+ The luminescence mechanism of doping Figure 7 Different concentrations of xMo are given 4+ -1.75%Te 4+ Doped Cs 2 SnCl 6 Medium 4+ The fluorescence lifetime at 568 nm emission can be seen as Mo 4+ With the increase of ion concentration, Te 4+ The fluorescence lifetime at 568 nm emission gradually decreases, indicating that Te 4+ Ions and Mo 4+ There is energy transfer between the ions. Figure 8 The 6.56%Mo given in 4+ -1.75%Te 4+ Doped Cs 2 SnCl 6 and 1.75%Te 4+ Doped Cs 2 SnCl 6 The time constant fitted by the excited state absorption signal can further confirm the existence of energy transfer, while the decrease in the amplitude of the defect-related time constant proves that Mo 4+ The ion introduction also effectively passivates defects in the material, ultimately resulting in efficient ultra-broadband emission.

[0032] In addition, we also studied the variable temperature spectrum of Mo near-infrared spectrum (4-300 K). Due to the suppression of lattice phonon and thermal vibrations, many sharp peaks appeared in the spectrum at low temperatures, and broad peaks were recorded at room temperature. In order to further study the electron-phonon interaction, the relationship between the half-peak width and temperature was fitted, and the Huang-Rhys factor S in the near-infrared region was obtained to be 2.54, and the Huang-Rhys factor in the visible region was 28.52. Generally speaking, the Huang-Rhys factor parameter can reflect the interaction strength of electron-phonon coupling. The lower the Huang-Rhys value, the weaker the electron-phonon coupling, resulting in a lower non-radiative transition rate. Therefore, phosphors with lower Huang-Rhys factors have higher PLQY. Compared with the recently reported Cr 3+ -Bi 3+ Co-doped Cs 2 Ag 0.6 Na 0.4 InCl 6 (PLQY = 26%) Visible emission S = 79.6, NIR emission S = 3.9 Compared to our Mo 4+ -Te 4+ Co-doped Cs 2 SnCl 6 The fitted S value of the system is lower, indicating that the electron-phonon coupling is weaker, further resulting in efficient emission (PLQY = 95.3%). Based on the above discussion, if Fig.11 As shown in the figure, we proposed Mo 4+ -Te 4+ Co-doped Cs 2 SnCl 6 Schematic diagram of the luminescence mechanism. Under 390 nm excitation, Te 4+ Ions from the ground state 1 S 0 Be inspired 3 P 1 excited state, and undergoes dynamic Jahn-Teller distortion, from 3 P 1 Energy level transition to 1 S 0 Produces a wide warm white light; at the same time, part of the excitation energy is from Te 4 +3 P 1 The excited state transfers to Mo 4+ energy level, and relaxes to the excited state energy level, producing the corresponding Mo 4+ Strong and broad near-infrared radiation.

[0033] Based on Mo 4+ -Te 4+ Co-doped Cs 2SnCl 6 We combined it with a commercial 395 nm chip to prepare an ultra-wide spectrum LED with both warm white light and near-infrared light, and used it in experiments to detect blood oxygen content using the characteristics of dual-spectrum emission of the LED. In addition, the LED was also used in white light illumination and night vision imaging, showing great application potential.

[0034] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. Transition metal and oxygen group element doped metal halide, characterized in that, The chemical formula of the transition metal and chalcogenide doped metal halide is Cs2Sn 1-x-y Cl6:x%Te 4+ ,yMo 4+ , 0<x≤50,0<y≤50.

2. The transition metal and oxygen group element doped metal halide according to claim 1, characterized in that: The 4+ The doping content is 1.75%, Mo 4+ The doping content is 6.56%; The transition metal and oxygen group element doped metal halide has a cubic crystal phase structure.

3. The method for preparing a transition metal and oxygen group element doped metal halide according to any one of claims 1 to 2, characterized in that: The following steps are involved: Step 1: Tellurium dioxide, tin tetrachloride pentahydrate, and molybdenum pentachloride are placed in a container containing a hydrochloric acid solution, and stirred thoroughly. Cesium carbonate dissolved in the hydrochloric acid solution is added to the container to precipitate and generate a reaction product; Step 2: The reaction product obtained in step 1 is purified by centrifugation several times with ethanol, and the purified precipitate is placed in an oven for drying to obtain the transition metal and oxygen group element doped metal halide.

4. The method for preparing transition metal and oxygen group element doped metal halide according to claim 3, characterized in that: The molar ratio of tellurium dioxide to tin tetrachloride pentahydrate in step 1 is 3:

17.

5. The method for preparing transition metal and oxygen group element doped metal halide according to claim 3, characterized in that: In step 1, the volume ratio of the hydrochloric acid solution contained in the container to the hydrochloric acid solution used to dissolve cesium carbonate is 5:

2.

6. The method for preparing transition metal and oxygen group element doped metal halide according to claim 3, characterized in that: The centrifugal speed for centrifugal purification in step 2 is 5000 rpm / min.

7. The method for preparing transition metal and oxygen group element doped metal halide according to claim 3, characterized in that: In step 2, the number of centrifugal purifications is 3 times, and the centrifugation time for each time is 5 min.

8. The method for preparing transition metal and oxygen group element doped metal halide according to claim 3, characterized in that: The oven temperature in step 2 is 80°C.

9. The method for preparing transition metal and oxygen group element doped metal halide according to claim 3, characterized in that: The drying time in step 2 is 12 h.

10. Use of the transition metal and oxygen group element doped metal halide as claimed in any one of claims 1 to 2 in night vision and blood gas analysis.

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