Preparation method of double perovskite halide Cs2AgInCl6 doped Mn < 2 + > ion photochromic powder

Abstract

The invention relates to the technical field of photochromism, in particular to a preparation method of double perovskite halide Cs2AgInCl6 doped Mn < 2 + > ion photochromic powder, and the preparation method of the white photochromic powder comprises the following steps: S1, weighing: weighing required amounts of AgCl and InCl3 on an analytical balance; s2, a MnCl2. 4H2O solution with the concentration of 1 mol / L is prepared, and the amount of the needed MnCl2. 4H2O solution is calculated according to different doping amounts; and S3, firstly proportioning AgCl, InCl3 and MnCl2. 4H2O solutions, heating, stirring and reacting in hydrochloric acid until the solutions are dissolved, stirring for 10 minutes, then adding CsCl, heating and stirring for 20 minutes, and centrifugally drying to obtain a sample. According to the invention, a chemical synthesis method is utilized, and manganese ions are doped in double perovskite halide Cs2AgInCl6, so that an obvious photochromic phenomenon is realized; the photochromic performance is regulated and controlled through an experimental method and the Mn < 2 + > doping concentration. And meanwhile, the exploration range of the inorganic halide photochromic material and the application range of the double perovskite halide are expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of photochromism, and particularly relates to a preparation method of a double perovskite halide Cs2AgInCl6 doped with Mn 2 + ion photochromic powder. Background Art

[0002] Some substances can undergo changes in optical properties under the stimulation of external fields (such as light fields, electric fields, magnetic fields, thermal fields, etc.). Among them, photochromism, electrochromism, thermochromism, etc. are relatively common. Among them, due to the good safety and easy operation of light field control, photochromism has received much attention in recent years.

[0003] Photochromism mainly refers to the change in optical properties of a material under the irradiation of light with a specific wavelength, thereby causing a change in the color of the sample. Photochromic materials are applied in fields such as optical storage, molecular switches, and anti-counterfeiting marks; in the prior art, photochromic materials are mainly divided into inorganic photochromic materials, organic photochromic materials, and organic-inorganic photochromic materials; among them, inorganic photochromic materials are commonly used in scientific research due to their more excellent thermal stability and longer service cycle life. Currently, the main inorganic photochromic materials mainly include: transition metal oxides (such as WO3, TiO2, etc.), strong oxides (BaMgSiO4, Ca2SnO2, etc.), ferroelectrics (Na 0.5 Bi 2.5 Nb2O9, Na 0.5 Bi 4.5 Ti4O 15 ,K 0.5 Na 0.5Oxide materials such as NbO3. Among the numerous reported oxide perovskite materials, although oxides have strong stability under harsh conditions, their large lattice formation energy (≈3000 kJ mol-1) requires a large amount of energy input to generate the phase. In fact, most oxides are produced by calcination at temperatures above 1000 °C, which brings considerable energy consumption and safety risks to manufacturers. In addition, the calcined powder phosphors have serious scattering problems, which hinder signal acquisition in basic research, so quantitative research on them is rarely carried out. In recent years, lead-free halide double perovskites (LHDPs) have attracted increasing attention due to their inherent advantages such as high absorption coefficient, low trap density, low toxicity, good stability, and high quantum yield (PLQY). As a new type of inorganic material, lead-free halide double perovskites show remarkable application prospects in the fields of photovoltaic materials, luminescent materials, photocatalysis, etc. However, in the field of photochromism, there are few relevant reports on lead-free halide double perovskites. Achieving obvious photochromic phenomena in lead-free halide double perovskites can not only expand the exploration scope of inorganic photochromic materials and provide a new direction for exploring inorganic photochromic materials with better performance, but also further expand the application scope of lead-free halide double perovskites.

[0004] Inorganic photochromism is usually related to the formation of color centers induced by vacancy defects or charge transfer caused by the valence electron jump in the chromophore. The formation of the valence electron jump in the chromophore is closely related to the variable valence of element ions in the material. The formation of the valence electron jump in the chromophore helps to improve the photochromic performance of the material. The oxygen vacancy content in inorganic photochromic materials can be increased by the following strategies: (1) Selecting appropriate excitation wavelengths: Different ions have specific absorption spectral ranges. By irradiating with light wavelengths that match the absorption peaks of the target variable valence ions, sufficient energy can be provided for the ions to achieve variable valence. For example, Cu 2+ , Mn 2+ , etc. can use specific visible light or ultraviolet light irradiation to make the ions absorb photon energy and then cross the energy level difference, thus achieving ion variable valence; (2) Introducing impurity cations: Introducing specific impurity cations into the lattice of double perovskite materials can promote ion variable valence by changing the electronic structure and local chemical environment of the crystal. For example, doping some metal ions with high redox activity (such as Fe 3+ , Co 2+ , etc.), which can interact with the host ions, change the charge distribution and coordination environment around the host ions, thereby reducing the energy barrier of ion variable valence and making the variable valence process easier to carry out. (3) Doping anions: Doping different halogen anions (such as Cl - , Br - , I -)It can also affect the electronic properties of the material. Different anions have different properties such as radius and electronegativity, which can lead to lattice distortion and changes in electron cloud density, thereby affecting the redox activity of the host ions and promoting ion valence change.

[0005] The existing Chinese patent CN201910191509.1 discloses a method for synthesizing highly fluorescent Mn-doped Cs2AgInCl6. First, cesium chloride, silver chloride, and indium chloride are mixed and ground. The mixture gradually hardens from a fluffy white powder and adheres to the container wall, then softens, and continues to be ground until the mixture becomes a fluffy white powder again. Then, manganese chloride is added and ground until the pink ultradry manganese chloride is evenly dispersed in the reaction system and the pink color disappears, and the grinding is stopped; the obtained product is washed with ethanol and dried in a vacuum at 60 - 350 °C for 2 hours to obtain highly fluorescent Mn2+:Cs2AgInCl6. Currently, the disclosed CN201910191509.1 only involves the improvement of fluorescence performance and does not mention the photochromic characteristics. In previous studies on Cs2AgInCl6 halide double perovskite photochromic materials, the research was basically focused on single crystals of Cs2AgInCl6, and the research scope was mostly on the luminescence regulation in this matrix system. The photochromic phenomenon was only reported, and the mechanism explanation of its photochromism was not clearly studied. In addition, different-sized materials are obtained through different synthesis methods, and their photochromic properties are studied through different materials.

[0006] Therefore, to solve the above problems, the present invention proposes a preparation method for two kinds of halide double perovskite Cs2AgInCl6 doped with Mn 2+ ion photochromic ceramic powder, and initial samples with white background color and light purple background color are synthesized respectively. Subsequently, research on luminescence regulation and photochromism is carried out on samples with different background colors. First, the presence of Ag element can generate more cationic defects. At the same time, Cs2AgInCl6 is usually synthesized by chemical methods. Finally, manganese ions are selected as the high-valence element as the doping element. By the above methods, the ion valence change content in the halide double perovskite Cs2AgInCl6 is increased, so as to achieve an obvious photochromic phenomenon in the halide double perovskite material. Summary of the Invention

[0007] The purpose of the present invention is to provide a preparation method for double perovskite halide Cs2AgInCl6 doped with Mn 2+ ion photochromic powder, which uses chemical synthesis method to achieve an obvious photochromic phenomenon by doping manganese ions in the double perovskite halide Cs2AgInCl6.

[0008] To achieve the above technical purposes and reach the above technical effects, the present invention is realized through the following technical solutions:

[0009] Preparation method of double perovskite halide Cs2AgInCl6 doped with Mn 2+ ions white photochromic powder, comprising the following steps:

[0010] S1: Weighing: Weigh the required amounts of AgCl and InCl3 on an analytical balance;

[0011] S2: Prepare a 1 mol / L MnCl2·4H2O solution, and calculate the required amount of MnCl2·4H2O solution according to different doping amounts;

[0012] S3: First, mix AgCl, InCl3, and MnCl2·4H2O solution well, then carry out heating and stirring reaction in hydrochloric acid until dissolved, stir for 10 min, then add CsCl, heat and stir for 20 min, and then centrifuge and dry to obtain the sample.

[0013] Further, the doped ion Mn in step S2 2+ (MnCl2·4H2O), the concentration is in mol percentage, wherein Mn 2+ accounts for 0.05 - 5 mol%. The Cs2AgInCl6 doped with Mn prepared by this method 2+ is white in the original state. When the surface is irradiated with ultraviolet light with a wavelength of 365 nm for a certain time, the surface area of the powder within the irradiated range will turn into gray with significant distinguishability.

[0014] Preparation method of double perovskite halide Cs2AgInCl6 doped with Mn 2+ ions light purple photochromic powder, comprising the following steps:

[0015] S1: Weighing: Weigh the required amounts of AgCl, InCl3, CsCl, and MnCl2·4H2O calculated according to different doping ratios on an analytical balance;

[0016] S2: Add hydrochloric acid, then stir and react for 30 min; centrifuge and dry to obtain the sample.

[0017] Further, the doped ion Mn in step S1 2+ (MnCl2·4H2O), the concentration is in mol percentage, wherein Mn 2+ accounts for 0.05 - 5 mol%. The Cs2AgInCl6 doped with Mn prepared by this method 2+ is light purple in the original state. When the surface is irradiated with ultraviolet light with a wavelength of 365 nm for a certain time, the surface area of the powder within the irradiated range will turn into gray with significant distinguishability.

[0018] Advantages of the present invention:

[0019] Mn 2+ The increase of 2+ activates the fluorescence performance of Cs2AgInCl6 and also increases its photochromic performance. The photochromic performances of the samples synthesized by the two methods in this product are different, and their luminescence performances are also different. The photochromic mechanism in this invention is that Ag + gains electrons to become Ag 0 , and interacts with Cl in the matrix to produce defects, resulting in the photochromic phenomenon. However, the photochromism of this invention is difficult to fade, and it has better stability compared with the performance of the conventional photochromic powders.

[0020] A double perovskite halide Cs2AgInCl6 doped with Mn proposed in this invention 2+ Two preparation methods of photochromic ceramic powder, obtaining two photochromic inorganic halide double perovskites Cs2AgInCl6:Mn with different background colors 2+ ; but since the photochromism of the purple powder is poorer compared with the white one, the photochromic material Cs2AgInCl6:Mn 2+ in this invention selects the white powder for further development. The photochromic material Cs2AgInCl6:Mn 2+ in this invention selects the white powder, which has excellent photochromic performance under ultraviolet excitation; the photochromic performance of the inorganic halide double perovskite Cs2AgInCl6 is regulated by doping with high-valent Mn 2+ ions: the photochromic performance is regulated by experimental methods and the concentration of doped Mn 2+ . At the same time, the exploration scope of inorganic halide photochromic materials and the application scope of double perovskite halides are expanded.

[0021] The photochromic powder Cs2AgInCl6:Mn 2+ in this invention can change from white or light purple to gray under the irradiation of a 365 nm ultraviolet lamp. The photochromic material Cs2AgInCl6:Mn 2+ in this invention has excellent photochromic performance under ultraviolet excitation and has excellent performance prospects when applied to fields such as information storage and anti-counterfeiting labels.

[0022] In this invention, by controlling the concentration of the doped ion Mn 2+ (MnCl2·4H2O) in mol percentage, the optimization regulation of the photochromic material can be realized, and the stability of the material and the controllability of the photochromic effect are improved, so as to obtain better photochromic effects and performances. The traditional halide double perovskite photochromic materials have stability problems during long-term use, and are prone to fading or losing the photochromic ability. By doping Mn 2+Ions can increase the content of ionic valence variation in double perovskite Cs2AgInCl6 and improve the stability of the material. Secondly, the addition of manganese ions can also activate the photoluminescence performance of the material and further improve its application prospects.

[0023] The manganese ion-doped photochromic powder of double perovskite Cs2AgInCl6 has broad application potential. In terms of anti-counterfeiting labels, this material has obvious color change characteristics and can be used to make anti-counterfeiting marks to improve the security and identifiability of products; in the field of sensors, the photochromic characteristics of this material can be used to make optical sensors to achieve rapid detection and monitoring of environmental parameters; in terms of optical storage and display materials, this material can be used to make high-density optical storage media and high-resolution display devices to improve the storage and display effects. This material not only has high thermal stability and service life, but also can achieve obvious photochromic effects, providing a reliable basis for its popularization in various application fields.

[0024] Of course, it is not necessary for any product implementing the present invention to simultaneously achieve all the above-mentioned advantages. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 XRD diagrams of Cs2AgInCl6, Cs2AgInCl6: 0.5 mol% Mn 2+ 、Cs2AgInCl6: 1 mol% Mn 2 + 、Cs2AgInCl6: 2 mol% Mn 2+ 、Cs2AgInCl6: 5 mol% Mn 2+ 、photochromic purple powder and white powder materials;

[0027] Figure 2 XRD diagrams of Cs2AgInCl6, Cs2AgInCl6: 1 mol% Mn 2+ (white powder), Cs2AgInCl6: 1 mol% Mn 2+ (purple powder) diffuse reflectance spectra of the photochromic material before and after irradiation under 365 nm ultraviolet light

[0028] Figure 3For Cs2AgInCl6 and Cs2AgInCl6: 0.5 mol% Mn described in Example 3 2+ 、Cs2AgInCl6: 1 mol% Mn 2 + 、Cs2AgInCl6: 2 mol% Mn 2+ 、Cs2AgInCl6: 5 mol% Mn 2+ Diffuse reflectance spectra of the photochromic white powder material before and after irradiation under 365 nm ultraviolet light;

[0029] Figure 4 For Cs2AgInCl6: 1 mol% Mn described in Example 4 2+ Color of the sample of the photochromic material before irradiation under 365 nm ultraviolet light;

[0030] Figure 5 For Cs2AgInCl6: 1 mol% Mn described in Example 5 2+ Color of the sample of the photochromic material after irradiation for 65 min under 365 nm ultraviolet light. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] Method 1: Injection method

[0033] S1: Weighing: Weigh the required amounts of AgCl and InCl3 on an analytical balance;

[0034] S2: Prepare a 1 mol / L MnCl2·4H2O solution and calculate the required amount of the MnCl2·4H2O solution according to different doping amounts;

[0035] S3: First, mix AgCl, InCl3, and the MnCl2·4H2O solution, then carry out a heating and stirring reaction in hydrochloric acid until dissolved, stir for 10 min, then add CsCl, heat and stir for 20 min, and then centrifuge and dry to obtain the sample

[0036] Further, the doped ion Mn in step S 2+ (MnCl2·4H2O), with the concentration in mol percentage, where Mn 2 + accounts for 0.5 - 5 mol%. The Cs2AgInCl6 doped with Mn prepared by this method2+ The original state is white. When the surface is irradiated with ultraviolet light with a wavelength of 365 nm for a certain period of time, the surface area of the powder within the irradiated range will turn into gray with significant distinctiveness.

[0037] Method 2:

[0038] S1: Weighing: Weigh the required amounts of AgCl, InCl3, CsCl, and MnCl2·4H2O calculated with different doping ratios on an analytical balance.

[0039] S2: After adding hydrochloric acid, stir and react for 30 min; centrifuge and dry to obtain the sample.

[0040] Furthermore, the doped ion Mn in step S1 2+ (MnCl2·4H2O), with the concentration in mol percentage, where Mn 2+ accounts for 0.5 - 5 mol%. The Cs2AgInCl6 doped with Mn prepared by this method 2+ is light purple in the original state. When the surface is irradiated with ultraviolet light with a wavelength of 365 nm for a certain period of time, the surface area of the ceramic powder within the irradiated range will turn into gray with significant distinctiveness.

[0041] Example 1

[0042] As Figure 1 shown

[0043] Perform X-ray diffraction analysis on the sample obtained by the above method to obtain an X-ray diffraction pattern. As Figure 1 shown, it can be seen from the figure that the diffraction peaks of this series of samples doped with different concentrations of Mn 2+ are all matched with the Cs2AgInCl6 standard card PDF NO. 24 - 4519, indicating that this series of samples are all in the Cs2AgInCl6 phase;

[0044] The pure phase indicates that only this compound exists in the sample, which means that the Mn 2+ ions have successfully entered the Cs2AgInCl6 lattice, that is, there are no compounds or impurities different from Cs2AgInCl6. Therefore, the effects obtained by the samples obtained through this application can accurately evaluate the characteristics and properties of Cs2AgInCl6:Mn 2+ .

[0045] Example 2

[0046] As Figure 2 shown, the influence of different concentrations of Mn 2+ doping on the photochromic performance of Cs2AgInCl6 powder was investigated.

[0047] The diffuse reflection spectra of Cs2AgInCl6 powder doped with different Mn ions before and after 365 nm light illumination were measured using a spectrophotometer (U-4100) equipped with an integrating sphere; 2+ ions before and after 365 nm light illumination;

[0048] The samples obtained in this application were irradiated with 365 nm ultraviolet light, and the diffuse reflection spectra of Cs2AgInCl6, Cs2AgInCl6: 0.5 mol% Mn 2+ , Cs2AgInCl6: 1 mol% Mn 2+ , Cs2AgInCl6: 2 mol% Mn 2+ , Cs2AgInCl6: 5 mol% Mn 2+ ceramic powders before and after color change were measured. As shown in Figure 2 , it can be seen that after the samples were irradiated with 365 nm ultraviolet light, the intensity of the diffuse reflection spectra in the range of 400 nm - 800 nm decreased. The results showed that after doping with 1 mol% Mn 2+ ions, the Cs2AgInCl6:Mn 2+ powder had the best color change effect.

[0049] Example 3

[0050] As shown in Figure 3 , 4 shown

[0051] By covering with a mask plate, under the irradiation of a 365 nm ultraviolet lamp, the writing of a light quality color change pattern can be achieved.

[0052] As shown in Figure 3 is a photo of Cs2AgInCl6: 1 mol% Mn 2+ ceramic powder before color change. The color of the powder is mainly white. Under the irradiation of a 365 nm ultraviolet lamp, it can be clearly found that the sample changes from white to gray.

[0053] The Cs2AgInCl6:Mn 2+ powder obtained in the present invention, when the synthesis temperature is 85 °C and the synthesis time is within 2 hours, a lead-free double perovskite halide with a photochromic effect is obtained, and the photochromic phenomenon shows the advantage of high contrast. It shows that the manganese ion-doped Cs2AgInCl6 double perovskite oxide with photochromic characteristics has broad application prospects in optical switches, optical storage, and optical detectors, etc.

[0054] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. Preparation method of double perovskite halide Cs2AgInCl6 doped with Mn 2+ ion photochromic powder, characterized in that The photochromic powder is white and includes the following steps: S1: Weighing: Weigh the required amounts of AgCl and InCl3 on an analytical balance. S2: Prepare a 1 mol / L MnCl2·4H2O solution and calculate the amount of the MnCl2·4H2O solution according to different doping amounts. S3: First, mix the AgCl, InCl3, and MnCl2·4H2O solution well, then carry out a heating and stirring reaction in hydrochloric acid until dissolved, stir for 10 min, then add CsCl, heat and stir for 20 min, and then centrifuge and dry to obtain the sample.

2. Preparation method of double perovskite halide Cs2AgInCl6 doped with Mn 2+ ion photochromic powder, characterized in that: The doped ion Mn in the step S2 2+ (MnCl2·4H2O), with the concentration in mol percentage, where Mn 2+ accounts for 0.05 to 5 mol%.

3. Preparation method of double perovskite halide Cs2AgInCl6 doped with Mn 2+ ion photochromic powder, characterized in that: Prepared Cs2AgInCl6 doped with Mn 2+ The original state of the sample is white. When the surface is irradiated with ultraviolet light with a wavelength of 365 nm for a certain period of time, the surface area of the powder within the irradiated range will turn into a gray color with significant distinctiveness.

4. Preparation method of double perovskite halide Cs2AgInCl6 doped with Mn 2+ ions and photochromic powder, characterized in that The photochromic powder is light purple and includes the following steps: S1: Weighing: Weigh the required amounts of AgCl, InCl3, CsCl, and MnCl2·4H2O calculated according to different doping ratios on an analytical balance. S2: Add hydrochloric acid and stir for 30 min; centrifuge and dry to obtain the sample.

5. Preparation method of double perovskite halide Cs2AgInCl6 doped with Mn 2+ ion photochromic powder, characterized in that: The doped ion Mn in the step S1 2+ (MnCl2·4H2O), the concentration is in mol percentage, where Mn 2+ accounts for 0.05 to 5 mol%.

6. Preparation method of double perovskite halide Cs2AgInCl6 doped with Mn 2+ ion photochromic powder, characterized in that: Prepared Cs2AgInCl6 doped with Mn 2+ The original state of the sample is light purple. When the surface is irradiated with ultraviolet light with a wavelength of 365 nm for a certain period of time, the surface area of the powder within the irradiated range will turn into gray with significant distinguishability.

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