Cesium-manganese-chlorine perovskite, preparation method thereof and near-infrared light-emitting diode device

Abstract

The invention provides cesium-manganese-chlorine perovskite, a preparation method thereof and a near-infrared light-emitting diode device, and relates to the technical field of preparation of light-emitting materials. According to the invention, manganese chloride and cesium chloride are used as raw materials, and coprecipitation reaction is carried out in hydrochloric acid and ethanol to obtain cesium-manganese-chloride perovskite with emission wavelength mainly at near-infrared band. Experimental results show that the fluorescence emission wave band of the cesium manganese chloride perovskite prepared by the preparation method provided by the invention is 700-850nm, and when the near-infrared light-emitting diode device is used as a light source, blood vessels in fingers in a hand photo shot by a near-infrared camera are clearly visible.

Description

Technical Field

[0001] The present invention belongs to the technical field of luminescent material preparation, and in particular relates to a cesium manganese chloride perovskite and a preparation method thereof, and a near-infrared light-emitting diode device. Background Art

[0002] Perovskites are a class of compounds with a specific crystal structure that exhibits excellent optoelectronic properties. Although rare earth-doped lead halide perovskites have been widely reported as potential near-infrared LEDs and solar light conversion layer materials, their further practical application is limited by the toxicity of lead.

[0003] Compared to lead-halide perovskites, lead-free perovskite materials have become a research focus in recent years due to their unique optical properties, such as low toxicity and good material stability, and have achieved significant progress. However, most current lead-free perovskite materials emit light in the visible light region. For example, cesium manganese chloride perovskite (CsMnCl3) emits light in the 400-700nm range, which is mainly concentrated in the visible light region.

[0004] Because biological tissues strongly scatter visible light, lead-free perovskite materials with a fluorescence wavelength between 400 and 700 nm, when used as light sources for bioluminescent imaging, can reduce the depth and clarity of images, hindering deep tissue imaging and image resolution. Therefore, there is a need for a lead-free perovskite material with near-infrared luminescence. Summary of the Invention

[0005] The present invention aims to provide a cesium manganese chloride perovskite, a preparation method thereof, and a near-infrared light-emitting diode device. The preparation method provided by the present invention can prepare a cesium manganese chloride perovskite with an emission band of 700-850 nm.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a method for preparing cesium manganese chloride perovskite, comprising the following steps: (1) mixing manganese chloride and a solvent and dissolving them to obtain a mixed solution; the solvent includes hydrochloric acid and ethanol; (2) The mixed solution obtained in step (1) is mixed with cesium chloride and subjected to a coprecipitation reaction to obtain cesium manganese chloride perovskite.

[0007] Preferably, a ligand is added when manganese chloride and the solvent are mixed in step (1), and the ligand is an amino acid and / or aminochloropyridine.

[0008] Preferably, the ligands are amino acids and aminochloropyridines, and the molar ratio of the amino acids to aminochloropyridines is 1:(1-3).

[0009] Preferably, the molar ratio of manganese chloride to ligand in step (1) is 1:(0.02-3).

[0010] Preferably, the manganese chloride in step (1) is manganese dichloride.

[0011] Preferably, the mass concentration of hydrochloric acid in step (1) is 36-38%, and the volume of hydrochloric acid is 10-40% of the volume of the solvent.

[0012] Preferably, the dissolution temperature in step (1) is 60-90° C., and the dissolution time is 20-40 min.

[0013] Preferably, the temperature of the coprecipitation reaction in step (2) is 60-90° C., and the coprecipitation reaction time is 20-40 min.

[0014] The present invention also provides cesium manganese chloride perovskite prepared by the preparation method described in the above technical solution, and the fluorescence emission band of the cesium manganese chloride perovskite is 700~850nm.

[0015] The present invention also provides a near-infrared light-emitting diode device, in which the light-conversion material is the cesium manganese chloride perovskite described in the above technical solution.

[0016] The present invention provides a method for preparing cesium manganese chloride perovskite, comprising: mixing manganese chloride and a solvent and dissolving them to obtain a mixed solution; the solvent comprises hydrochloric acid and ethanol; and mixing the mixed solution with cesium chloride and performing a coprecipitation reaction to obtain cesium manganese chloride perovskite. The present invention uses manganese chloride and cesium chloride as raw materials, and through a coprecipitation reaction in hydrochloric acid and ethanol, obtains cesium manganese chloride perovskite with an emission wavelength mainly in the near-infrared band. This can suppress the autofluorescence effect of biological tissues and enhance the penetration depth of fluorescence in biological tissues, which is beneficial for deep tissue imaging and imaging resolution. Experimental results show that the fluorescence emission band of the cesium manganese chloride perovskite prepared by the preparation method provided by the present invention is 700~850nm. When the near-infrared light-emitting diode device is used as a light source, the blood vessels in the fingers are clearly visible in the hand photos taken with a near-infrared camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a comparison chart of the X-ray powder diffraction pattern of the cesium manganese chloride perovskite prepared in Examples 1 and 2 of the present invention and a standard card; Figure 2 This is a comparison chart of the X-ray powder diffraction pattern of the cesium manganese chloride perovskite prepared in Comparative Example 1 of the present invention and a standard card; Figure 3 This is a comparison chart of the X-ray powder diffraction pattern of the cesium manganese chloride perovskite prepared in Comparative Example 2 of the present invention and a standard card; Figure 4 This is an excitation spectrum of the cesium manganese chloride perovskite prepared in Example 1 of the present invention; Figure 5 Graphs showing emission spectra of cesium manganese chloride perovskites prepared in Examples 1 to 5 of the present invention; Figure 6 The excitation and emission spectra of cesium manganese chloride perovskite prepared in Comparative Example 1 of the present invention are shown; Figure 7 Schematic diagram of the structure of the near-infrared emitting diode of the present invention, wherein 1 is an aluminum-based heat sink, 2 is an LED chip, and 3 is a mixed layer; Figure 8 This is an emission spectrum diagram of the near-infrared emitting diode device of Example 6 of the present invention at different currents; Figure 9 The hand photo is taken with a near-infrared camera using the near-infrared emitting diode device of Example 6 of the present invention as the illumination light source. DETAILED DESCRIPTION

[0018] The present invention provides a method for preparing cesium manganese chloride perovskite, comprising the following steps: (1) mixing manganese chloride and a solvent and dissolving them to obtain a mixed solution; the solvent includes hydrochloric acid and ethanol; (2) The mixed solution obtained in step (1) is mixed with cesium chloride and subjected to a coprecipitation reaction to obtain cesium manganese chloride perovskite.

[0019] The present invention mixes manganese chloride and a solvent and then dissolves them to obtain a mixed solution.

[0020] In the present invention, the manganese chloride is preferably manganese dichloride. The present invention does not particularly limit the source of the manganese dichloride, and commercially available manganese dichloride can be used. The manganese dichloride of the present invention is the manganese source and chlorine source of the cesium manganese chloride perovskite. Compared with other types of manganese chloride, manganese dichloride has good solubility in common solvents and can be mixed with other reactants to form a more uniform reaction system.

[0021] In the present invention, the solvent includes hydrochloric acid and ethanol. By selecting hydrochloric acid and ethanol as solvents for the coprecipitation reaction, the present invention not only realizes the controllable transformation of the crystal structure from CsMnCl3 to Cs2MnCl4(H2O)2, but also realizes the coupling of Mn in Cs2MnCl4(H2O)2. 2+ -Mn 2+ dimer 4 T 1g - 6 A 1g The emission wavelength can also be red-shifted from the visible light region to the near-infrared band.

[0022] In the present invention, the mass concentration of the hydrochloric acid is preferably 36-38%, more preferably 37%; the ethanol is preferably analytical pure ethanol; and the volume of the hydrochloric acid is preferably 10-40% of the volume of the solvent, more preferably 20-40%.

[0023] In the present invention, the volume ratio of the solvent to the amount of manganese chloride is preferably 5 to 20 L:1 mol, more preferably 10 L:1 mol. The present invention can ensure the stability of the crystal structure Cs2MnCl4(H2O)2 by controlling the proportion and addition amount of each solvent component.

[0024] In the present invention, when the manganese chloride and the solvent are mixed, a ligand is preferably added, wherein the ligand is preferably an amino acid and / or aminochloropyridine, more preferably an amino acid and aminochloropyridine; the amino acid is preferably one or more of 5-aminopentanoic acid, 6-aminohexanoic acid and 7-aminoheptanoic acid, more preferably 5-aminopentanoic acid; the aminochloropyridine is preferably one or more of 3-amino-2-chloropyridine, 2-chloro-3-aminopyridine, 3-chloro-2-aminopyridine, 5-chloro-2-aminopyridine and 2-chloro-4-aminopyridine, more preferably 3-amino-2-chloropyridine. The present invention can improve the luminescence intensity by introducing the above-mentioned ligand system.

[0025] In the present invention, the molar ratio of the amino acid to the aminochloropyridine is preferably 1:(1-3), more preferably 1: 3. By controlling the ratio of the ligands within the above range, the luminescence intensity can be further improved.

[0026] In the present invention, the molar ratio of manganese chloride to ligand is preferably 1:(0.02-3), more preferably 1:(0.3-3). As one embodiment of the present invention, the molar ratio of manganese chloride to ligand can be 1:0.1, 1:0.4, or 1:1. By controlling the molar ratio of manganese chloride to ligand, the present invention further ensures an increase in luminescence intensity.

[0027] The present invention does not specifically limit the operation of mixing the manganese chloride and the solvent, and a technical solution familiar to those skilled in the art can be used. In an embodiment of the present invention, the manganese chloride is preferably weighed first and then added to the solvent. When a ligand is added to the manganese chloride and solvent, the manganese chloride and ligand are preferably weighed first, mixed evenly, and then added to the solvent.

[0028] In the present invention, the dissolution is preferably performed under stirring; the dissolution temperature is preferably 60-90°C, more preferably 80°C; the dissolution time is preferably 20-40 minutes, more preferably 30 minutes; and in an embodiment of the present invention, the dissolution is preferably performed in an oil bath. Under the above-mentioned dissolution conditions of temperature and time, a uniform mixed solution is obtained.

[0029] After obtaining the mixed solution, the present invention mixes the mixed solution with cesium chloride and then performs a coprecipitation reaction to obtain cesium manganese chloride perovskite.

[0030] The present invention does not specifically limit the source of the cesium chloride; commercially available cesium chloride can be used. The cesium chloride of the present invention is a cesium source and a chlorine source for the cesium manganese chloride perovskite. Cesium chloride is readily soluble in water and common organic solvents and can be easily mixed with other precursors to form a uniform reaction system. The introduction of cesium ions can significantly improve the thermal and light stability of the perovskite material.

[0031] In the present invention, the mixed solution and cesium chloride are preferably mixed by adding cesium chloride into the mixed solution.

[0032] In the present invention, the coprecipitation reaction is preferably carried out under stirring; the temperature of the coprecipitation reaction is preferably 60-90° C., more preferably 80° C., and the time of the coprecipitation reaction is preferably 20-40 min, more preferably 30 min.

[0033] After the coprecipitation reaction is completed, the present invention preferably subjects the obtained product to a first centrifugation, washing and a second centrifugation in sequence to obtain cesium manganese chloride perovskite. In the present invention, the rotation speed of the first and second centrifugations are independently preferably 4000~6000r / min, more preferably 5000r / min; the time of the first and second centrifugations are independently preferably 3~10min, more preferably 5min; the washing solvent is preferably methanol; the number of washings is preferably 3~4 times; the washing method is preferably ultrasound; and the time of ultrasound treatment is preferably 3~6min. The present invention can achieve solid-liquid separation under the above-mentioned centrifugal treatment speed and time. Methanol is a relatively mild solvent, which is very effective in removing organic residues and impurities on the surface of cesium manganese chloride perovskite. ， It will not damage the perovskite crystal structure.

[0034] The present invention also provides a cesium manganese chloride perovskite prepared by the preparation method described in the above technical solution, wherein the fluorescence emission band of the cesium manganese chloride perovskite is 700-850 nm. In the present invention, the fluorescence emission band of the cesium manganese chloride perovskite is 700-850 nm, mainly in the near-infrared region.

[0035] The present invention also provides a near-infrared light-emitting diode device, in which the light-conversion material is the cesium manganese chloride perovskite described in the above technical solution.

[0036] In the present invention, the near-infrared light-emitting diode device preferably includes an aluminum-based heat sink, an LED chip, and a mixed layer stacked in sequence; the mixed layer includes cesium manganese chloride perovskite and an organic packaging material.

[0037] In the present invention, the thickness of the aluminum-based heat sink is preferably 1 to 3 mm. The present invention has no special requirements on the source of the aluminum-based heat sink, and commercially available aluminum-based heat sinks can be used.

[0038] In the embodiment of the present invention, the emission wavelength of the LED chip is preferably 350 nm. The present invention has no special requirements on the source of the LED chip, and commercially available ones can be used.

[0039] In the present invention, the thickness of the mixed layer is preferably 0.5-2 mm. In the present invention, the mixed layer preferably includes cesium manganese chloride perovskite and an organic encapsulating material; the mass ratio of the cesium manganese chloride perovskite to the volume ratio of the organic encapsulating material is preferably 0.1-1 mg / μL. In the present invention, the organic encapsulating material is preferably polymethyl methacrylate or UV-curable acrylic adhesive, and the molecular weight of the organic encapsulating material is preferably 100.12 Da. In an embodiment of the present invention, the organic encapsulating material is UV-curable acrylic adhesive, and the molecular weight of the UV-curable acrylic adhesive is 100.12 Da.

[0040] In the present invention, the method for preparing the near-infrared light-emitting diode device preferably comprises the following steps: 1) mixing cesium manganese chloride perovskite with an organic encapsulation material to obtain a mixture; 2) coating the mixture obtained in step 1) on an LED chip and then performing UV curing to obtain a near-infrared emitting LED chip; 3) Soldering the near-infrared light-emitting LED chip obtained in step 2) onto an aluminum-based heat sink to obtain a near-infrared light-emitting diode device.

[0041] In the present invention, cesium manganese chloride perovskite is preferably mixed with an organic encapsulation material to obtain a mixture.

[0042] In the present invention, the mass ratio of the cesium manganese chloride perovskite to the volume ratio of the organic encapsulating material is preferably 0.1 to 1 mg / μL. The present invention has no specific limitation on the mixing method, as long as a uniform mixture can be obtained.

[0043] After obtaining the mixture, the present invention preferably coats the mixture on an LED chip and then performs ultraviolet light curing to obtain a near-infrared emitting LED chip.

[0044] In the present invention, the coating amount of the mixture is preferably 20-50 μL, more preferably 40 μL. The LED chip is preferably an LED chip with an emission wavelength of 350 nm. In the present invention, the UV curing time is preferably 20 minutes.

[0045] After obtaining the near-infrared light-emitting LED chip, the present invention preferably welds the near-infrared light-emitting LED chip onto an aluminum-based heat sink to obtain a near-infrared light-emitting diode device.

[0046] In the present invention, the welding is preferably performed by tin welding.

[0047] The near-infrared light-emitting diode device prepared by the present invention has good stability when used as a light source, and blood vessels in fingers are clearly visible in a hand photo taken with a near-infrared camera.

[0048] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] Example 1 The preparation method of cesium manganese chloride perovskite is: (1) Weigh 1 mmol of manganese dichloride, 0.1 mmol of 5-aminovaleric acid, and 0.3 mmol of 3-amino-2-chloropyridine, mix them evenly, add them to a solvent obtained by mixing 2 mL of concentrated hydrochloric acid (37%) and 8 mL of ethanol (analytical grade), and stir in an oil bath at 80°C for 30 min to dissolve them to obtain a mixed solution; (2) 3 mmol of cesium chloride was added to the mixed solution and stirred at 80 °C for 30 min to perform a co-precipitation reaction. The mixture was cooled to room temperature and centrifuged at 5000 r / min for 5 min to achieve solid-liquid separation. The precipitate was ultrasonically washed with methanol 4 times, each ultrasonic washing for 5 min. The cesium manganese chloride perovskite was obtained after a second centrifugation at 5000 r / min for 5 min.

[0050] The emission band of cesium manganese chloride perovskite is 700~850nm, and its crystal structure is Cs2MnCl4(H2O)2.

[0051] Example 2 The difference between the preparation method of Example 2 and that of Example 1 is that step (1) is different: (1) Weigh 1 mmol of manganese dichloride, 1.5 mmol of 5-aminovaleric acid, and 1.5 mmol of 3-amino-2-chloropyridine, mix them evenly, add them to a solvent obtained by mixing 4 mL of concentrated hydrochloric acid (37%) and 6 mL of ethanol (analytical grade), and stir in an oil bath at 80°C for 30 min to dissolve them to obtain a mixed solution.

[0052] The emission band of cesium manganese chloride perovskite is 700~850nm, and its crystal structure is Cs2MnCl4(H2O)2.

[0053] Example 3 The difference between the preparation method of Example 3 and that of Example 1 is that step (1) is different: (1) Weigh 1 mmol of manganese dichloride and 0.3 mmol of 3-amino-2-chloropyridine, mix them evenly, add them to a solvent obtained by mixing 2 mL of concentrated hydrochloric acid (37%) and 8 mL of ethanol (analytical grade), and stir in an oil bath at 80°C for 30 min to dissolve them to obtain a mixed solution.

[0054] The emission band of cesium manganese chloride perovskite is 700~850nm, and its crystal structure is Cs2MnCl4(H2O)2.

[0055] Example 4 The difference between the preparation method of Example 4 and that of Example 1 is that step (1) is different: (1) Weigh 1 mmol of manganese dichloride and 0.5 mmol of 5-aminovaleric acid, mix them evenly, add them to a solvent obtained by mixing 2 mL of concentrated hydrochloric acid (37%) and 8 mL of ethanol (analytical grade), and stir in an oil bath at 80°C for 30 min to dissolve them to obtain a mixed solution.

[0056] The emission band of cesium manganese chloride perovskite is 700~850nm, and its crystal structure is Cs2MnCl4(H2O)2.

[0057] Example 5 The difference between the preparation method of Example 5 and that of Example 1 is that step (1) is different: (1) Weigh 1 mmol of manganese dichloride and add it to a solvent obtained by mixing 2 mL of concentrated hydrochloric acid (37%) and 8 mL of ethanol (analytical grade). Stir in an oil bath at 80°C for 30 min to dissolve the solution to obtain a mixed solution.

[0058] The emission band of cesium manganese chloride perovskite is 700~850nm, and its crystal structure is Cs2MnCl4(H2O)2.

[0059] Example 6 The schematic structural diagram of the near-infrared light-emitting diode of Example 6 is shown in FIG. Figure 9 As shown, an aluminum-based heat sink, an LED chip, and a mixed layer are stacked in sequence; the mixed layer is composed of the cesium manganese chloride perovskite obtained in Example 1 and an organic packaging material.

[0060] The preparation method of the near-infrared emitting diode device is as follows: (1) Cesium manganese chloride perovskite and an organic encapsulation material (AA352 type UV light curing acrylic adhesive with a molecular weight of 100.12 Da) were mixed uniformly at a mass volume ratio of 1 mg / μL to obtain a mixture; (2) The obtained mixture was coated on a blue LED chip with an emission wavelength of 350 nm (coating area of ​​9 mm) at a coating volume of 40 μL. 2 ), the thickness of the mixed layer is 2 mm, and it is irradiated under 365 nm ultraviolet light for 20 min to cure to obtain a near-infrared emitting LED chip; (3) The obtained near-infrared light-emitting LED chip is soldered to an aluminum-based heat sink (2 mm thick) with tin to obtain a near-infrared light-emitting diode device.

[0061] Comparative Example 1 The difference between the preparation method of Comparative Example 1 and Example 1 is that step (1) is different: Weigh 1 mmol of manganese dichloride, add it to 10 mL of concentrated hydrochloric acid, and stir in an oil bath at 80° C. for 30 min to dissolve it to obtain a mixed solution.

[0062] The emission band of cesium manganese chloride perovskite is 550~800nm, and its crystal structure is CsMnCl3.

[0063] Comparative Example 2 The cesium manganese chloride perovskite of Comparative Example 2 is 0D-C2MC4H in the English literature “Zero- and One-Dimensional Lead-Free Perovskites for Photoelectrochemical Applications”, and its crystal structure is Cs2MnCl4(H2O)2.

[0064] The emission band of cesium manganese chloride perovskite is 450~700nm, and its crystal structure is Cs2MnCl4(H2O)2.

[0065] The cesium manganese chloride perovskite obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were tested by X-ray diffractometer. The obtained X-ray powder diffraction patterns were compared with those of the standard cards. Figures 1-3 shown.

[0066] from Figure 1 Comparison of the X-ray powder diffraction patterns of the cesium manganese chloride perovskite prepared in Examples 1 and 2 of the present invention with the standard card 21-0214 shows that the peak positions of all characteristic diffraction peaks completely match those of the standard card, and the peak positions and relative intensities of all characteristic diffraction peaks are consistent with those of the PDF standard card, indicating that the samples prepared in Examples 1 and 2 are pure phase Cs2MnCl4(H2O)2, the samples are highly crystalline, and the obtained samples belong to the triclinic p space group.

[0067] Figure 2 The X-ray powder diffraction pattern of the cesium manganese chloride perovskite prepared in Comparative Example 1 of the present invention is compared with the standard card 20-0280. It can be seen that all diffraction peaks match well with the peak positions of the standard PDF card, indicating that the sample prepared in Comparative Example 1 is pure phase CsMnCl3 and the sample is highly crystalline.

[0068] Figure 3 Comparison of the X-ray powder diffraction pattern of the cesium manganese chloride perovskite prepared in Comparative Example 2 of the present invention with the standard card 21-0214 shows that the XRD spectrum of the Cs2MnCl4(H2O)2 sample in the prior art of Comparative Example 2 shows obvious peak position shift and relative intensity difference, indicating that there is lattice distortion or that the preferred growth directions of each crystal plane during crystal growth are different, resulting in crystal orientation differences.

[0069] The cesium manganese chloride perovskite prepared in Example 1 was subjected to a fluorescence spectrometer, and the wavelength of the excitation light source was gradually changed. The emission fluorescence intensity of the sample was recorded at each excitation wavelength. The obtained excitation spectrum is shown in FIG. Figure 4 As shown; the cesium manganese chloride perovskite prepared in Examples 1 to 5 was tested by fluorescence spectrometer with an incident light of 355 nm, and the emission spectrum obtained was as shown in FIG. Figure 5 As shown; the cesium manganese chloride perovskite prepared in Comparative Example 1 was tested for excitation spectrum using a fluorescence spectrometer using the above method to obtain an excitation spectrum diagram, and an incident light of 370 nm was selected for emission spectrum testing, and the obtained emission spectrum diagram was as shown Figure 6 shown.

[0070] from Figure 4 It can be seen that the excitation spectrum of the cesium manganese chloride perovskite prepared in Example 1 is composed of three (355 nm, 421 nm and 513 nm) excitation peaks with distinct structures, and the emission fluorescence intensity is the highest under incident light at 355 nm.

[0071] from Figure 5 It can be seen that the samples of Examples 1 to 5 emit near-infrared light in the range of 710 to 850 nm under excitation of incident light at 355 nm. When only 3-amino-2-chloropyridine or 5-aminopentanoic acid is added to Examples 3 and 4, the emission intensity is much lower than that of Examples 1 and 2 in which both 5-aminopentanoic acid and 3-amino-2-chloropyridine are added. The emission intensity of the sample prepared in Example 5 without adding a ligand in the near-infrared region is weak.

[0072] from Figure 6It can be seen that the cesium manganese chloride perovskite prepared in Comparative Example 1 has the highest fluorescence emission intensity under incident light at 370 nm. When excited by incident light with the strongest excitation peak of 370 nm, the emitted light is mainly visible light centered at 650 nm. Compared with Example 5, since the solvent in the reaction process is only hydrochloric acid without ethanol, the prepared perovskite crystal is CsMnCl3. When excited by incident light with the strongest excitation peak of 370 nm, the emitted light is mainly visible light centered at 650 nm, and the near-infrared light emission is not obvious.

[0073] The near-infrared light-emitting diode device obtained in Example 6 was tested at different currents (20~200mA, with an increment of 20mA) using a Labsphere integrating sphere and a USB-4000 spectrometer to obtain the near-infrared emission spectrum of the LED device. Figure 8 shown.

[0074] from Figure 8 It can be seen that the emission intensity gradually increases from 20 mA to 200 mA, and the peak position of the emission wavelength of the device does not change and has not yet reached the threshold, which fully proves that the near-infrared light-emitting diode device of Example 6 has good stability.

[0075] The bioluminescence imaging was performed using the near-infrared light emitting diode device of Example 6 as the illumination light source, and a near-infrared camera was used to take a photo of the hand to obtain Figure 9 .

[0076] from Figure 9 It can be seen that the blood vessels in the fingers are clearly visible.

[0077] It can be seen from the above embodiments and comparative examples that the fluorescence emission band of the cesium manganese chloride perovskite prepared by the preparation method provided by the present invention is 700~850nm; the emission intensity is enhanced when a ligand is added; when the near-infrared light-emitting diode device is used as a light source for bioluminescence imaging, the blood vessels in the fingers of the hand photographs taken are clearly visible; the near-infrared light-emitting diode device prepared using cesium manganese chloride perovskite as a light conversion material, when the emission intensity gradually increases from 20mA to 200mA, the peak position of the emission wavelength does not change, and has not reached the threshold, and has good stability.

[0078] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing cesium manganese chloride perovskite, comprising the following steps: (1) mixing manganese chloride and a solvent and dissolving them to obtain a mixed solution; the solvent includes hydrochloric acid and ethanol; (2) The mixed solution obtained in step (1) is mixed with cesium chloride and subjected to a coprecipitation reaction to obtain cesium manganese chloride perovskite.

2. The preparation method according to claim 1, characterized in that In the step (1), a ligand is added when manganese chloride and the solvent are mixed, and the ligand is an amino acid and / or aminochloropyridine.

3. The preparation method according to claim 2, characterized in that The ligands are amino acids and aminochloropyridine, and the molar ratio of the amino acids to aminochloropyridine is 1:(1-3).

4. The preparation method according to claim 2 or 3, characterized in that In the step (1), the molar ratio of manganese chloride to the ligand is 1:(0.02-3).

5. The preparation method according to claim 1 or 2, characterized in that The manganese chloride in step (1) is manganese dichloride.

6. The preparation method according to claim 1 or 2, characterized in that The mass concentration of hydrochloric acid in step (1) is 36-38%, and the volume of hydrochloric acid is 10-40% of the volume of the solvent.

7. The preparation method according to claim 1 or 2, characterized in that The dissolution temperature in step (1) is 60-90° C., and the dissolution time is 20-40 min.

8. The preparation method according to claim 1 or 2, characterized in that The temperature of the co-precipitation reaction in step (2) is 60-90° C., and the co-precipitation reaction time is 20-40 min.

9. The cesium manganese chloride perovskite prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The fluorescence emission band of the cesium manganese chloride perovskite is 700-850 nm.

10. A near-infrared light-emitting diode device, characterized in that: The light conversion material in the near-infrared light-emitting diode device is the cesium manganese chloride perovskite described in claim 9.

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