Multiple excitation source metal halide and method of making

Abstract

This invention relates to the field of manganese metal halide technology, specifically to a metal halide with multiple excitation sources. The metal halide has the structural formula A2[MnCl4], where A is CTP or BTP, CTP is (2-chlorobenzyl)triphenylphosphonium cation, and BTP is benzyltriphenylphosphonium cation. The preparation method of the metal halide includes step 1: dissolving MnCl2 and substance A in methanol at room temperature to form a clear and transparent solution; step 2: slowly evaporating the solution from step 1 in an oven for 48 hours to prepare a light green blocky A2[MnCl4] single crystal. The (CTP)2MnCl4 and (BTP)2MnCl4 prepared by this invention exhibit defect-assisted four-coordinated Mn at 513 and 516 nm, respectively. 2+ The strong green light emission generated by the d-d transitions of the CTP2MnCl4 and BTP2MnCl4 photoluminescence quantum yields reached as high as 98.5% and 88.4%, respectively. Based on commercial CsI:Tl scintillators, the photoluminescence yields of the CTP2MnCl4 and BTP2MnCl4 scintillators were calculated to be as high as approximately 89,000 and 49,000 photons / MeV, respectively. The scintillator screen of CTP2MnCl4@PDMS also achieved high-resolution X-ray imaging with a speed of up to 9.1 lp / mm.

Description

Technical Field

[0001] This invention relates to the field of manganese metal halide technology, specifically to a metal halide with multiple excitation sources and its preparation method. Background Technology

[0002] In the past decade or so, CsPbX3 (X=Cl) has been used as a base. - , Br - I - Three-dimensional (3D) lead halide perovskite semiconductor materials, represented by lead halide, are becoming promising materials for light-emitting diodes (LEDs), solar cells, radiation detection, and other optoelectronic devices due to their low-cost wet chemical synthesis and excellent optoelectronic properties, such as high carrier mobility, suitable band gap, high photoluminescence quantum yield (PLQY), and strong X-ray absorption. However, the poor toxicity and stability of lead halide perovskites greatly limit their further development. Therefore, finding alternatives to lead-based halides has become a hot research topic.

[0003] In this regard, environmentally friendly and low-cost organic-inorganic hybrid zero-dimensional (0D)Mn 2+ Manganese-based metal halides, as a novel class of luminescent materials, exhibit outstanding optical properties under ultraviolet / blue light, X-rays, and mechanical stimulation, leading to their rapid development in the field of optoelectronic devices, particularly in wide color gamut backlight displays, flexible wearable optoelectronic products, X-ray detection, and anti-counterfeiting encryption. However, most reported manganese-based metal halides can only be excited by a single or dual excitation source. Manganese-based metal halides capable of simultaneous excitation by ultraviolet / blue light, X-rays, and mechanical force are rarely reported. Therefore, exploring manganese metal halides with multiple excitation sources and their applications in various scenarios has significant scientific and practical value.

[0004] In the field of mechanoluminescence, mechanoluminescent materials have been applied in information storage, structural damage sensors, pressure sensors, and anti-counterfeiting devices. Unlike the elastomechanical luminescence mechanism commonly found in doped inorganic compounds (such as ZnS:Cu, ZnS:Mn, and CaZnOS:Mn), metal halides typically exhibit fracture-mechanical luminescence, and their mechanoluminescence is usually so weak as to be difficult to detect. Although there are numerous reports on mechanoluminescent manganese-based metal halides, further research is needed to understand their detailed fracture luminescence process and mechanism. In the field of X-ray detection, indirect X-ray imaging is widely used, in which the scintillator is a key component. Although various types of materials have been used as X-ray scintillators, existing organic and inorganic scintillators still have many problems and limitations. For example, inorganic crystals are difficult to grow and have strict requirements for hygroscopicity, while organic crystals exhibit anisotropic scintillation. Low-dimensional metal halide scintillators, represented by lead halides, have become promising X-ray scintillators due to their high X-ray absorption coefficient, ease of solution processing, and high scintillation yield.

[0005] However, the commercial development of lead halide scintillators has been hampered by problems such as poor lead stability and toxicity. Most recently reported zero-deployment (OD) lead-free, high-efficiency metal halide scintillators are based on inorganic cations such as copper, manganese, tin, and antimony. Among them, Mn(II)-based metal halides are the most promising candidate materials for X-ray imaging due to their advantages such as low toxicity, negligible self-absorption, high photoluminescence quantum yield (PLQY), and high scintillation rate. In the field of wearable optoelectronics, current wearable devices mostly focus on the application of APbX3. The obstacles to practical application are the instability of lead halide perovskites under light, humidity, and temperature, harmful lead ion leakage, and the difficulty in manufacturing uniform flexible films at large scale and high productivity. Encapsulating metal halides in polymers, porous alumina films, or manufacturing metal halide-transparent glass composites have been developed to stabilize metal halides and endow them with advanced optoelectronic functions. However, these methods require some complex synthesis and processing steps (such as spin coating and high-temperature quenching processes) and it is difficult to obtain large-area flexible metal halide films. In recent years, electrospinning technology has proven to be one of the most ideal methods for preparing perovskite luminescent fiber films, and the prepared luminescent films or devices can be easily assembled into large-area, flexible, and wearable optoelectronic products. Therefore, combining metal halides with electrospinning technology to synthesize smart wearable optoelectronic flexible films on a large scale has great application prospects. Summary of the Invention

[0006] To comprehensively address the aforementioned problems, this invention aims to design a metal halide with multiple excitation sources. Two novel manganese-based metal halides, (CTP)₂MnCl₄ and (BTP)₂MnCl₄ (CTP being (2-chlorobenzyl)triphenylphosphonium ion and BTP being benzyltriphenylphosphonium chloride ion), were synthesized. Their crystal structures were determined, their fluorescence spectra, quantum yields, and thermal stability were measured, and their luminescence mechanisms were analyzed.

[0007] (CTP)₂MnCl₄ and (BTP)₂MnCl₄ exhibit defect-assisted tetracoordinated Mn at 513 and 516 nm, respectively. 2+ The strong green light emission generated by the dd transition of the scintillator showed photoluminescence quantum yields (PLQY) as high as 98.5% and 88.4%, respectively. Both scintillators exhibited strong stress luminescence upon crystal fracture, and the flexible film prepared using them also achieved excellent force-stimulated luminescence. Based on the commercial CsI:Tl scintillator, the luminescence yields of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ scintillators were calculated to be approximately 89,000 and 49,000 photons / MeV, respectively. The (CTP)₂MnCl₄@PDMS scintillator screen also achieved X-ray imaging with a resolution as high as 9.1 lp / mm. Subsequently, (CTP)₂MnCl₄ was combined with PMMA to prepare a large-area luminescent fiber film of 20cm × 25cm, which can be used in fields such as wearable luminescent clothing for nighttime emergency rescue, information recording, and emergency lighting.

[0008] To achieve the above objectives, the first aspect of the present invention provides a metal halide with multiple excitation sources, having the structural formula A2[MnCl4], wherein A is CTP or BTP, CTP is (2-chlorobenzyl)triphenylphosphonium cation, and BTP is benzyltriphenylphosphonium cation.

[0009] A second aspect of the present invention provides a method for preparing metal halides with multiple excitation sources, comprising:

[0010] Step 1: Dissolve MnCl2 and substance A in methanol at room temperature to form a clear and transparent solution;

[0011] Step 2: The solution from Step 1 was slowly evaporated in an oven for 48 hours to prepare light green blocky A2[MnCl4] single crystals.

[0012] Preferably, the molar ratio of MnCl2 to substance A in step 1 is 1:2.

[0013] Preferably, the temperature of the oven in step 2 is 40°C.

[0014] Preferably, substance A in step 1 is either (2-chlorobenzyl)triphenylphosphonium chloride or benzyltriphenylphosphonium chloride.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] The (CTP)₂MnCl₄ and (BTP)₂MnCl₄ synthesized in this invention exhibit defect-assisted tetracoordinated Mn at 513 and 516 nm, respectively. 2+ The strong green light emission generated by the dd transition of the scintillator showed photoluminescence quantum yields (PLQY) as high as 98.5% and 88.4%, respectively. Both scintillators exhibited strong stress luminescence upon crystal fracture, and the flexible films prepared using them also achieved excellent force-stimulated luminescence. Based on commercial CsI:Tl scintillators, the luminescence yields of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ scintillators were calculated to be approximately 89,000 and 49,000 photons / MeV, respectively. The scintillator screen of (CTP)₂MnCl₄@PDMS also achieved high-resolution X-ray imaging with a rate as high as 9.1 lp / mm. Subsequently, (CTP)₂MnCl₄ was combined with PMMA to prepare a large-area luminescent fiber film of 20cm × 25cm, which can be used in fields such as wearable luminescent clothing for nighttime emergency rescue, information recording, and emergency lighting. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0018] In the attached diagram:

[0019] Figure 1 In the image, a. Photographs of (CTP)₂MnCl₄ under fluorescent light (top) and 365nm ultraviolet light excitation (bottom); b. Photographs of (BTP)₂MnCl₄ single crystals under fluorescent light (top) and 365nm ultraviolet light excitation (bottom); c. Scanning electron microscope image of (CTP)₂MnCl₄ single crystal, showing the elemental distribution of Cl, P, and Mn; d. Scanning electron microscope image of (BTP)₂MnCl₄ single crystal, showing the elemental distribution of Cl, P, and Mn; e. Ellipsoidal diagram of the molecular structure of (CTP)₂MnCl₄ (50% probability ellipsoid); f. Ellipsoidal diagram of the molecular structure of (BTP)₂MnCl₄ (50% probability ellipsoid); g. Crystal structure of (CTP)₂MnCl₄; h. Crystal structure of (BTP)₂MnCl₄.

[0020] Figure 2In the diagram, a. excitation and emission spectra of (CTP)₂MnCl₄; b. excitation and emission spectra of (BTP)₂MnCl₄; c. relationship between excitation power and emission intensity of (CTP)₂MnCl₄; d. relationship between excitation power and emission intensity of (BTP)₂MnCl₄; e. fluorescence decay spectra of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ at room temperature; f. fluorescence quantum yield of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ at room temperature; g. UV-vis absorption spectra of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ at room temperature; h. photoluminescence mechanism diagram of (CTP)₂MnCl₄ and (BTP)₂MnCl₄.

[0021] Figure 3 Among them, a. temperature-dependent PL spectrum of (CTP)₂MnCl₄; b. temperature-dependent PL spectrum of (BTP)₂MnCl₄; c. thermogravimetric analysis and differential thermal analysis of (CTP)₂MnCl₄; d. thermogravimetric analysis and differential thermal analysis of (BTP)₂MnCl₄; e. photoluminescence stability of (CTP)₂MnCl₄ in air, at 80℃, 25℃ and 78% relative humidity; f. photoluminescence stability of (BTP)₂MnCl₄ in air, at 80℃, 25℃ and 78% relative humidity.

[0022] Figure 4 In the image, a. Mechanoluminescence and photoluminescence spectra of (CTP)₂MnCl₄; b. Mechanoluminescence and photoluminescence spectra of (BTP)₂MnCl₄; c. Force response of (CTP)₂MnCl₄ over time; d. Force response of (BTP)₂MnCl₄ over time; e. PL and PLE spectra of (CTP)₂MnCl₄ single crystal before and after fracture at room temperature; f. PL ​​and PLE spectra of (BTP)₂MnCl₄ single crystal before and after fracture at room temperature; g. Schematic diagram of the mechanoluminescence mechanism; h. Photographs of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ force-responsive films under different conditions.

[0023] Figure 5In this paper, we present: a. the relationship between the absorption coefficients and photon energy of (CTP)₂MnCl₄, (BTP)₂MnCl₄, and CsI:Tl scintillators; b. the radiative emission spectra of (CTP)₂MnCl₄, (BTP)₂MnCl₄, and CsI:Tl scintillators under the same conditions; c. a comparison of the scintillation yields of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ with those of common scintillator crystals; d. the radiative emission spectra of (CTP)₂MnCl₄ and e. (BTP)₂MnCl₄ under the same conditions. f. The linear relationship between the radiative emission spectrum and luminescence intensity of (CTP)2MnCl4 and (BTP)2MnCl4 and the X-ray irradiation dose in the range of 14-926 μGyair / s; g. The linear relationship between the radiative emission intensity of (CTP)2MnCl4 and (BTP)2MnCl4 and the X-ray irradiation dose at low doses; h. Photographs of different objects under natural light, X-rays, and (CTP)2MnCl4@PDMS scintillation screen; h. The MTF curve of (CTP)2MnCl4@PDMS scintillation screen measured by the hypotenuse method.

[0024] Figure 6 In the image, a. Schematic diagram of the electrospinning process; b. Photograph of (CTP)2MnCl4@PVA fiber membrane under fluorescent light; c. Photograph of (CTP)2MnCl4@PVA fiber membrane under 254nm ultraviolet light; d. SEM image of (CTP)2MnCl4@PVA fiber membrane; e. Statistical distribution of diameter of (CTP)2MnCl4@PVA fibers; f. SEM image and elemental distribution map of (CTP)2MnCl4@PVA; g. Photograph of wearable luminescent clothing made from (CTP)2MnCl4@PVA fiber membrane; h. Luminescent bracelet; i. Luminescent digits; j. Emergency sign. Detailed Implementation

[0025] The following combination Figures 1-6 Preferred embodiments of the present invention will be described herein; it should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the present invention.

[0026] Example 1:

[0027] A metal halide with multiple excitation sources; structural formula A2[MnCl4]; wherein; A is a monovalent organophosphorus ion; A is CTP or BTP; CTP is (2-chlorobenzyl)triphenylphosphorus cation; BTP is benzyltriphenylphosphorus cation.

[0028] Example 2:

[0029] A method for preparing metal halides with multiple excitation sources; including

[0030] Step 1: Dissolve 1 mmol of MnCl2 and 2 mmol of substance A (substance A is (2-chlorobenzyl)triphenylphosphonium chloride or benzyltriphenylphosphonium chloride) in 10 mL of methanol at room temperature; a clear and transparent solution is formed.

[0031] Step 2: The solution from Step 1 was slowly evaporated in an oven at 40°C for 48 hours to obtain light green blocky A2[MnCl4] single crystals.

[0032] Results analysis:

[0033] 1. Crystal growth and structure:

[0034] Single crystals of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ were grown using a solvent evaporation method; both exhibited a transparent pale green color under sunlight and a bright green luminescence under 365nm ultraviolet light excitation. Figure 1 a and Figure 1 (b). Single crystal of (CTP)2MnCl4 (e.g.) Figure 1 (As shown in the upper right corner of a); dimensions are 1.0cm × 1.2cm × 1.7cm; shape is a regular polyhedron.

[0035] SEM and elemental distribution ( Figure 1 c and Figure 1 As shown in d), P, Cl, and Mn elements are uniformly distributed in the synthesized (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals, demonstrating that the synthesized crystals have high phase purity. The crystal structures of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ were determined by single-crystal X-ray diffraction (SCXRD); their crystal structure data are shown in Table 1. Figure 1 China and Figure 1 As shown in f; each (CTP)₂MnCl₄ and (BTP)₂MnCl₄ molecule contains two organic cations and one [MnCl₄] cation. 2- Tetrahedral anion; in terms of spatial structure; [MnCl4] 2- The tetrahedron is surrounded by the organic cation CTP. + / BTP + Separated; each [MnCl4] 2- There are no common vertices between them; a zero-dimensional structure is formed at the molecular level. The closest distances between Mn and Mn in (CTP)₂MnCl₄ and (BTP)₂MnCl₄ are 10.4233 and 10.4233, respectively. ( Figure 1 Zhongg and Figure 1 (h); A larger Mn-Mn distance can effectively prevent Mn from entering the atmosphere. 2+ Nonradiative transitions between ions; suppression of emission quenching; improvement of photoluminescence quantum yield.

[0036] Table 1. X-ray diffraction data of single crystals of (CTP)₂MnCl₄ and (BTP)₂MnCl₄

[0037]

[0038] 2. Photoluminescence properties

[0039] The excitation and emission spectra of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ indicate that ( Figure 2 a, Figure 2 (b) In the range of 200-500 nm, there are 6 main excitation peaks that can excite (CTP)₂MnCl₄ and (BTP)₂MnCl₄ crystals, corresponding to Mn₂ and Mn₂, respectively. 2+ of 6 A1→ 4 T1( 4 F)(287 / 289nm), 6 A1→ 4 E( 4 D)(359nm), 6 A1→ 4 T2( 4 D)(381nm), 6 A1→ 4 A1( 4 G), 4 E( 4 G)(433nm), 6 A1→ 4 T2( 4 G)(450nm), 6 A1→ 4 T1( 4 The G)(468nm) transition occurs, with the strongest excitation peak located at 287 / 289nm. Under different excitation wavelengths, narrow-band (~46nm) green light emission at 513 / 516nm is generated.

[0040] To further investigate the luminescence dynamics of (CTP)₂MnCl₄ and (BTP)₂MnCl₄, we measured their emission spectra at different powers. The power-variable spectra of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ can be well fitted by a single exponential function. Figure 2 c in the middle Figure 2 (d) At high power densities, their PL intensity gradually weakens and tends to stabilize (because the number of electrons trapped by the defect energy level is limited), indicating that their luminescence process is likely related to the defect-related excited state. These defect energy levels can serve as long-lived energy storage reservoirs for electrons, compensating for electrons to the emission center.

[0041] Their fluorescence decay lifetimes were measured using time-resolved spectroscopy; the results showed that the fluorescence lifetimes of both reached the millisecond level, at 3.147 and 3.118 ms, respectively. Figure 2 (e) The longer fluorescence decay lifetime is mainly due to the spin-forbidden nature of the d–d transitions at the metal center. This lifetime is higher than that of common tetrahedral bromides; this is because the spin-orbit coupling of chlorine atoms is lower than that of bromine atoms. Both also have high photoluminescence quantum yields; 98.5% and 88.4% respectively (Figure 2f); this is higher than most manganese-based metal halides reported in the current literature.

[0042] In addition, the ultraviolet-visible absorption spectrum ( Figure 2 Mn was observed in g) 2+ The characteristic transition peaks exhibit absorption tailing, further confirming the existence of defect levels. For bulk ionic metal halides, halide / metal vacancies, interstitials, and antisites are common structural defects in the formation of bulk components; however, due to the high crystallinity of the material, surface defects are negligible. Shallow and deep defects formed in the band gap play different decisive roles in the photophysical processes of the material; deep defects are known to be nonradiative recombination centers, shortening carrier lifetime and deteriorating optical performance; while shallow defects may be PL centers. Shallow defects are usually formed in the presence of halide vacancies; these vacancies are close to the valence band edge and may act as defect levels to locate photogenerated carriers undergoing radiative recombination.

[0043] The defects in (CTP)₂MnCl₄ and (BTP)₂MnCl₄ can be reasonably attributed to shallow defects caused by Cl vacancies. The photoluminescence mechanism of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ is as follows: Figure 2 As shown in Figure h; under ultraviolet or blue light excitation, electrons are first excited to shallow defect levels located at the edge of the valence band; then they are further excited to Mn 2+ The different excited state energy levels; then return to the ground state to produce green light emission.

[0044] 3. Stability

[0045] First, the thermal stability of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ was tested by variable-temperature spectroscopy; their variable-temperature spectra showed that ( Figure 3 a, Figure 3(b) During the temperature increase from 298 K to 478 K, the luminescence intensity gradually decreased to 19.1% and 18.4% of the initial values. Furthermore, with increasing temperature, a significant blue shift occurred in the emission peak position, accompanied by an increase in the full width at half maximum (FWHM). The increase in FWHM may be related to a reduction in electron-phonon coupling; while the blue shift in PL may be due to the filling of defect states with lower energies; this has also been reported in many other metal halides.

[0046] Subsequently, the thermal stability of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ was further tested by thermogravimetric analysis; such as Figure 3 c in the middle Figure 3 As shown in Figure d, (CTP)₂MnCl₄ and (BTP)₂MnCl₄ showed almost no weight loss and no endothermic or exothermic peaks at 537 K and 477 K, respectively; the endothermic peaks around 540 K and 482 K in the DTA results correspond to the melting points of (CTP)₂MnCl₄ and (BTP)₂MnCl₄, respectively, indicating high thermal stability. Furthermore, we measured the stability of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ during storage in water, heat, and air. After one month of exposure to air...

[0047] The spectral intensities of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ remained above 90% of their initial values; after being placed at 80°C for one month, the spectral intensities of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ remained above 86% of their initial values; after being stored at 25°C and 78% relative humidity for one month, their spectral intensities also remained above 80% of their initial intensities. Figure 3 e, Figure 3 (f)

[0048] 4. Mechatronic properties and applications

[0049] (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals can also emit a very bright green light under stress; this green light can be clearly observed even in sunlight. When stress is slowly applied to (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals, causing them to fracture, a very strong green light emission is produced at the instant of crystal fracture; such as... Figure 4 a, Figure 4 As shown in the illustration in Figure b. To further investigate its mechanoluminescence process, we further studied the mechanoluminescence spectra of (CTP)₂MnCl₄ and (BTP)₂MnCl₄. Figure 4 a, Figure 4(b) Their mechanoluminescence spectra show green emission peaks at 513 and 516 nm, respectively, almost coinciding with the photoluminescence peak positions. Similar TL and PL spectra indicate that their green emission originates from Mn. 2+ The same transition. Figure 4 c in the middle Figure 4 As can be seen from d, the mechanoluminescence signal exhibits good responsiveness over time. To further investigate the mechanoluminescence process, we compared the spectra of the bulk crystal before fracture and the microcrystals after fracture. Figure 4 e, Figure 4 (f)

[0050] The results show that the excitation and emission spectral intensities changed dramatically before and after the fracture; in addition to 6 A1→ 4 T1( 4 The emission spectrum intensity generated by the F) transition did not change significantly; the emission spectrum intensity generated by the other transitions decreased significantly; the strongest excitation peak changed from 450 nm to 284 nm; this indicates that the energy inside the crystal changed significantly before and after the fracture.

[0051] Figure 4 Figure g illustrates the mechanism of mechanoluminescence. Under mechanical stimulation, hydrogen bonds break at the fracture surface of the crystal, generating opposite charges. The energy released by the recombination of electrons and holes is then transferred to the same excited state as in photoluminescence, resulting in green light emission similar to photoluminescence. However, the breaking of hydrogen bonds is not a macroscopic process that can be sustained indefinitely. While breaking hydrogen bonds can be easily achieved from bulk crystals to microcrystals, leading to strong mechanoluminescence, further grinding of microcrystals makes it difficult to achieve the same breaking. This explains the non-reproducibility of observed mechanoluminescence.

[0052] Furthermore, since the excitation source for mechanoluminescence originates from the energy released during the recombination of electrons and holes within the crystal during fracture, when a crystal completely breaks from a bulk crystal into microcrystals, the energy released during the recombination of electrons and holes is used to excite mechanoluminescence, resulting in a significant energy difference between the bulk crystal and the microcrystals. This further explains the large difference in excitation and emission spectral intensities between the bulk crystal and the microcrystal. Subsequently, we combined (CTP)₂MnCl₄ and (BTP)₂MnCl₄ with silica gel to successfully prepare two flexible force-responsive films (Figure 4h). Both exhibit a uniform milky white color under sunlight and a bright green color under 254 nm ultraviolet light. Under stress stimulation, they can exhibit very obvious green light emission, which holds promise for information encryption and anti-counterfeiting identification.

[0053] 5. Radiative luminescence properties and applications

[0054] (CTP)₂MnCl₄ and (BTP)₂MnCl₄ also possess excellent radiative luminescence properties, showing broad application prospects in X-ray detection and imaging. We first calculated the X-ray absorption coefficients of (CTP)₂MnCl₄, (BTP)₂MnCl₄, and the typical scintillator CsI:TI over a wide photon energy range using a photon cross-section database. Figure 5 (a) Due to their very similar molecular formulas, (CTP)₂MnCl₄ and (BTP)₂MnCl₄ have essentially the same absorption rate. Furthermore, due to their lower density, their absorption rate in the medical digital radiography region (i.e., 18-30 keV) is slightly lower than that of CsI:Tl. Single crystals of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ exhibit bright green radiative emission under X-ray excitation. Figure 5 (Figure 5b, inset); and further measured the RL spectrum; exhibiting narrow-band green emission at 516 / 520 nm (Figure 5b); similar PL and RL spectra indicate that the same radiative recombination channel occurred under X-ray and ultraviolet excitation. Using a commercial CsI:Tl single-crystal scintillator (light yield approximately 54000 photons / MeV) as a reference, we further evaluated the light yields of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals. The responses of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals were approximately 1.64 and 0.91 times that of CsI:Tl; the calculated light yields of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals were approximately 89000 and 49000 photons / MeV, respectively; this is superior to most common inorganic scintillators currently available and reported in the literature. Figure 5 (c)

[0055] Furthermore, the RL spectral intensities of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals exhibited good linear response in the range of X-ray dose increasing from 214 μGyair / s to 926 μGyair / s. Figure 5 d, Figure 5 (e). Based on the linear response relationship of the RL spectrum at low X-ray doses, when the signal-to-noise ratio (SNR) is 3, the calculated detection limits of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals are 0.205 and 0.248 μGyair / s, respectively (Figure 5f), which are far lower than the 5.5 μGyair / s required for X-ray medical diagnosis. Given the excellent scintillation performance of (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals, we further verified their potential in practical X-ray imaging using (CTP)₂MnCl₄ as an example. A flexible scintillation screen prepared by mixing (CTP)₂MnCl₄ powder with PDMS was used for X-ray imaging. Figure 5 As shown in g1, we used a plastic capsule as the first target object; the plastic capsule contained a metal spring; normally, the spring cannot be observed under visible light. However, due to the different absorption capabilities of the metal spring and the plastic capsule for X-rays, we observed a contrasting image under X-ray irradiation; showing a clear metal spring inside.

[0056] To further demonstrate the capabilities of the X-ray imaging system, we used different chips as target objects. Under X-ray irradiation, some details of the internal circuitry of the microchips were revealed. Figure 5 (g234); demonstrated the potential of (CTP)2MnCl4@PDMS scintillation screens in industrial flaw detection. To characterize the spatial resolution of X-ray imaging, the modulation transfer function (MTF) of the image was obtained using the bevel method. Figure 5 As shown in h; when the MTF value is 0.2; the spatial resolution of the (CTP)2MnCl4@PDMS scintillator is 9.1 lp / mm; it shows great potential in practical X-ray imaging applications such as security inspection, non-destructive testing and medical radiology.

[0057] 6. Applications of multifunctional fiber membranes

[0058] Based on the enormous application potential of electrospinning technology in the field of wearable optoelectronics and the excellent optical properties and stability of (CTP)2MnCl4, the application of (CTP)2MnCl4 in multifunctional wearable luminescent fiber membranes was further explored. Figure 6 Figure a illustrates the preparation process of the (CTP)2MnCl4@PMMA luminescent fiber membrane. After filtering (CTP)2MnCl4 through a 100-mesh sieve, it is mixed evenly with a gelled polymethyl methacrylate (PMMA) aqueous solution. The mixture is then drawn up with a syringe and spun uniformly onto a rotating roller covered with oiled paper using a single-nozzle electrospinning device. After spinning for a period of time, a large-area fiber membrane of 20cm × 25cm is obtained. Figure 6 (b) The fiber membrane can be prepared repeatedly; under 254 nm ultraviolet light ( Figure 6 c); it exhibits uniform green light emission. Further analysis of the microstructure of the (CTP)2MnCl4@PMMA fiber membrane using SEM revealed that the membrane is composed of a spatial network structure spun from countless fine fibers. Figure 6 (d); The diameter distribution diagram shows that the average size of the fibers in the (CTP)2MnCl4@PMMA fiber membrane is 113.46 nm. Figure 6(e) Each fiber filament exhibits uniform size and no obvious beading or agglomeration, further demonstrating the uniformity of the prepared (CTP)₂MnCl₄@PMMA fiber membrane. Elemental mapping shows that C, O, P, Cl, and Mn are all uniformly distributed in the fiber membrane. Figure 6 (f)

[0059] Given the excellent optical properties of (CTP)2MnCl4@PMMA fiber films, we explored their application in night vision displays. First, wearable night vision clothing was fabricated using (CTP)2MnCl4@PMMA fiber films; large-area "SOS" and striped patterns were printed on it. Figure 6 (g); secondly, a fluorescent bracelet was prepared using this fiber membrane. Figure 6 (h); In the event of danger at night or in other emergencies; People wearing (CTP)2MnCl4@PMMA fiber night vision clothing can be quickly located and send out an "SOS" distress signal; It is expected to be used for rapid rescue in various emergency situations.

[0060] In addition; such as Figure 6 The fluorescent digit "0406" shown in the image is illustrated; the prepared fiber membrane can also be used for nighttime displays. We further explored its application in nighttime signage; traditional signs such as emergency exits are easily affected by external factors, leading to poor wiring and consequently, the LEDs not being fully activated. Based on the excellent optical properties of the (CTP)2MnCl4@PMMA fiber membrane, we designed an emergency exit sign that uses ultraviolet light to excite the luminescent fiber membrane. Figure 6 (j); This sign only requires a 254nm ultraviolet chip; which is much cheaper than traditional emergency exit signs.

[0061] In summary, the (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals prepared by this invention using a simple solvent evaporation method exhibit excellent photophysical properties; they can produce bright narrow-band green light emission under ultraviolet / blue light, mechanical force, and X-ray excitation; this green light emission originates from defect-assisted four-coordinated Mn 2+The dd transition occurs. For photoluminescence, (CTP)₂MnCl₄ and (BTP)₂MnCl₄ exhibit quantum yields as high as 98.5% and 88.4%, respectively. Wearable luminescent textiles based on (CTP)₂MnCl₄@PMMA fiber films can be used for emergency rescue in various emergency situations; they can also be used for various safety signs, offering greater convenience and cost-effectiveness compared to traditional signs. For X-ray detection, (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals have achieved light yields as high as 89,000 and 49,000 photons / MeV, respectively, outperforming most inorganic scintillators. For mechanoluminescence, the luminescence originates from the energy released by the recombination of electrons and holes during hydrogen bond breaking. Flexible films based on (CTP)₂MnCl₄ and (BTP)₂MnCl₄ can achieve good mechanoluminescence, showing promise for anti-counterfeiting identification.

[0062] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments; the embodiments and descriptions in the specification are merely illustrative of the principles of the invention; various changes and modifications can be made to the invention without departing from its spirit and scope; all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A metal halide with multiple excitation sources, characterized in that: The structural formula is A2[MnCl4], where A is a (2-chlorobenzyl)triphenylphosphine cation.

2. The method for preparing metal halides with multiple excitation sources as described in claim 1, characterized in that: include Step 1: Dissolve MnCl2 and (2-chlorobenzyl)triphenylphosphine chloride in methanol at room temperature to form a clear and transparent solution; Step 2: The solution from Step 1 was slowly evaporated in an oven for 48 hours to prepare light green blocky A2[MnCl4] single crystals.

3. The method for preparing metal halides with multiple excitation sources according to claim 2, characterized in that: In step 1, the molar ratio of MnCl2 to (2-chlorobenzyl)triphenylphosphine chloride is 1:

2.

4. The method for preparing metal halides with multiple excitation sources according to claim 3, characterized in that: The oven temperature in step 2 is 40℃.

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